\ 

1 


ERRATA. 


lead— 

"  Daguerrean,   Page  19 

:*  Daguerrean,      -       -       -       -       -              -  "21 

;£  Cyanide  of  Potassium,  (III.)   "  35 

"  Fluoride  of  Potassium,  (III.)       ....  •-<  35 

"  Marten,  *       -  "  43 

"  Iodide  first  word  on   "45 

"  Bromide  of  Ammonium,      (XI.)  -       -  "  45 

•'  Cyanide  of  Potassium,  (XII.)     ....  «  46 

Fluoride  of  Potassium,  (XII.)       -       -       -       -  "46 

•<  Bromide  of  Potassium,  (XIII.)    -       -       -       -  :c  46 

"  Cyanide,   "62 

"  Iodide  of  Ammonium,  (Haloid  Salts,)  -       -       -  "79 

"  Hypochlorite  of  potash,       -       -         -       -       -  "80 

"  N.H3,  (Formula,)   "83 

"  N.  for  Az.,   «•  121 

"  Cadmium  (after  Bromine.)  Cd.  696,8  55,8        -  "  148 


Digitized  by  the  Internet  Archive 
in  2014 


https://archive.org/details/photographynewtrOOheat 


A  PHOTOGRAPH  OF 
SIR    HUMPHREY  DAVY. 

THE  FIRST  EXPERIMENTER  IN  PHOTOGRAPHY. 


PHOTOGRAPHY 


NEW  TREATISE, 


THEOKETICAL  AND  PKACTICAL 


THE  PROCESSES  AND  MANIPULATIONS 


PAPER 


DRIED  AND  WET: 


GLASS, 

COLLODION  AND  ALBUMEN. 


BY  A.  S.  HEATH,  M.  D.,  AND  A.  H.  HEATH, 

CHEMISTS. 


NEW  YORK: 
PUBLISHED  BY  HEATH  &  BROTHER, 

AT  324  BROADWAY. 

1855. 


Entered  according  to  Act  of  Congress,  in  the  year  1855, 

By  HEATH  &  BEOTHEB, 

In  the  Clerk's  Office  of  the  District  Court  for  the  Southern  District  of 
New  Tork. 


PREFACE. 


Among  the  many  modem  inventions  and  dis- 
coveries, Photography  claims  attention  as  a  val- 
uable and  pleasant  aid  to  m%  and  an  important 
auxiliary  to  science  and  industry. 

Photography  has  made  such  rapid  progress  in 
the  improvement  of  apparatus,  that  but  little  is  left 
even  to  embellish  its  paraphernalia. 

The  word  Photography  (from  the  Greek  pw<ro£, 
light,  and  /papw,  I  write)  is  used  to  designate  the 
art  or  process  of  fixing  images  of  objects  in  the 
camera  ohscura,  on  any  sensitive  surface,  as  of 
metal,  glass,  paper,  &c,  previously  coated  with 
chemicals,  which  are  blackened  or  colored  by  the 
action  of  light. 

After  the  discoveries  of  Daguerre  and  Mepce, 
Mr.  Talbot  made  some  successful  experiments  in 
this  art  in  England,  where  soon  after  he  published 
his  process  called  Calotype,  Talbotype,  &c. 

A  great  number  of  experiments  have  been 
made  to  obtain  "  sensitive  matters ;"  as  yet  but 


4 


PREFACE. 


one  substance  has  succeeded,  viz.,  the  salts  of 
silver. 

The  iodide  of  silver  is  always  the  principal 
agent.  The  mixture  of  the  iodide  with  the  fluoride, 
cyanide,  chloride,  bromide,  ammonide,  phosphate, 
carbonate,  acetate,  &c,  of  silver,  is  very  good  to 
accelerate  the  formation  of  images,  but  used  alone 
they  do  not  produce  very  good  results.  We  do 
not  at  present  think  it  possible  to  perfect  the 
process  without  the  salts  of  silver. 

One  of  the  happiest  combinations  is  the  union 
of  iodide,  fluoride,  and  cyanide  of  potassium,  for 
we  have  made  experiments  with  iodide  alone ; 
iodide  and  cyanide ;  iodide  and  fluoride ;  iodide, 
cyanide,  and  fluoride.  The  last  formula  is  the 
best,  giving  the  most  satisfactory  results.  By 
using  this  triple  salt  at  the  moment  it  is  formed, 
proofs  may  be  obtained  in  two  seconds  in  summer, 
and  in  thirty  seconds  in  winter. 

It  is  very  important  to  procure  good  paper, 
which  would  be  much  more  easily  obtained  if 
some  experienced  paper-manufacturer  would  make 
photographic  paper  exclusively.  This  plan  we 
shall  endeavor  to  secure. 

The  process  on  glass,  it  is  true,  gives  proofs 
much  better  than  the  process  on  paper,  but  is  pro- 


PREFACE. 


5 


ductive  of  some  inconvenience.  Glass  is  difficult 
to  prepare,  not  convenient  to  handle,  and  it  does 
not  receive  the  image  as  quick  "as  paper.  A  proof 
on  glass  is  fine,  but  hard  and  rigid  ;  but  with 
collodion  you  have  a  good  and  a  very  sensitive 
plate. 

Besides  the  utility  of  Photography  in  obtaining 
portraits  and  views,  in  Europe  the  arts  and  sci- 
ences are  aided  by  it.  Nothing  is  more  easy  than 
to  take  pictures  of  insects,  animals,  plants,  inani- 
mate objects,  &c,  for  naturalists,  physiologists, 
pathologists,  and  botanists.  And  especially  is  it 
useful  in  the  mechanical  arts.  Nothing  is  more 
difficult  and  tedious  than  an  accurate  drawing  of 
complex  and  complicated  machinery.  By  Pho- 
tography every  desired  view  may  be  taken,  and 
with  correct  proportions  and  details,  of  the  most 
intricate  mechanism. 

In  Europe  the  art  has  arrived  to  a  high  degree 
of  perfection.  In  this  country  it  is  now  being  prac- 
tised with  success.  In  France  and  in  England  a 
great  many  books  have  been  published  upon  the 
various  branches  of  photography,  photology,  and 
photogenic  chemistry.  But  few  or  no  complete 
practical  works,  especially  adapted  to  teach  and 

guide  the  amateur  successfully  through  the  mazy 
1* 


6 


PREFACE. 


labyrinths  of  the  art  of  picture-taking,  have  been 
published  in  this  country. 

We  publish  this  work  with  the  hope  that  in  it 
will  be  found  all  necessary  information  to  the  easy 
and  successful  practice  of  Photography.  In  it  will 
be  found  all  the  new  processes,  having  consulted 
every  valuable  source  of  information  from  Paris, 
London,  and  in  this  country.  "We  give  also  the 
preparation  of  chemical  products,  and  the  best  tests 
of  their  purity.  The  phenomena  of  light  have  been 
treated  of,  on  which  subject,  unhappily,  too  many 
photographists  are  deficient. 

In  the  preparation  of  this  book  much  care  and 
attention  have  been  given ;  and  if  it  is  the  means 
of  improving  and  advancing  this  beautiful  art,  we 
shall  be  abundantly  rewarded. 

"We  take  great  pleasure  in  acknowledging  the 
valuable  services  of  Monsieur  H.  Dussauce,  of 
Paris,  and  of  those  of  the  venerable  Dr.  Moore,  of 
this  city,  who,  though  an  aged  gentleman,  is  an 
ardent  and  most  successful  photographist,  at  whose 
suggestion  the  Astor  Library  has  been  enriched 
with  most  of  the  foreign  books  on  this  subject. 

A.  S.  Heath,  M.  D. 
A.  H.  Heath. 

New  York,  June,  1855. 


CONTENTS. 


PAGE 

Introduction   11 

Part  I. — The  Daguerreian  Process   21 

I.  Choice  of  Plates   21 

II.  Polishing  Plates   22 

III.  Iodizing  the  Plate   23 

IV.  Exposure  to  the  Camera   23 

V.  Exposure  to  Mercury   23 

VI.  Washing  with  Hyposulphate  of  Soda   24 

VII.  Fixing  by  Chloride  of  Gold   24 

Accelerating  Liquors  '   25 

I.  Chloride  of  Iodine   25 

II.  Bromide  of  Iodine — Gaudin's  Preparation   26 

"             "       Claudet's  Preparation   26 

u             "       De  Valicourt's  Preparation   27 

HI.  Chloro-Bromide  of  Iodine   27 

Liquids  which  are  Substituted  eor  the  Iodizing  Box   28 

I.  Thierry's  Liquid   28 

II.  Iodide  of  Bromine   28 

III.  German  Liquid   29 

Part  II. — Process  on  Paper   33 

I.  Process  on  Waxed  Paper — Selection  of  Paper   33 

II.  Preparation  of  the  Waxed  Paper   34 

III.  Sensibilization   35 

IV.  Exciting   36 

V.  Exposure.   37 

VI.  Developing  of  the  Image   37 

VII.  Fixing   38 

VIII.  Process  on  Wet  Paper   39 

IX.  Process  on  Albumenized  Paper   40 


8  CONTENTS. 

PAGE 

X.  Different  Processes   41 

Talbot's  Process   41 

Bingham's  Process   42 

Channing's  Method   42 

Cundell's  Process   43 

Martin's  Method   43 

Jordan's  Method   44 

Thomas's  Method   44 

XI.  Negative  Method  with  Albumen   45 

XII.  Preparation  of  a  Special  Paper  for  Portraits   46 

XIII.  Negative  Paper  with  Gelatine   46 

XIV.  Negative  Paper  with  Alcohol   47 

XV.  Negative  Paper  with  the  Ammoniaco-Citrate  of  Iron.  47 

Part  III. — Process  on  Glass   51 

I.  Collodion. — Cleaning  the  Glass   51 

II.  Preparation  of  Collodion   51 

III.  Application   53 

IV.  Sensitive  Bath   53 

V.  Exposure  in  the  Camera   54 

VI.  Developing  ,   55 

VII.  Fixing  the  Proof   57 

VIII.  To  Transfer  the  Negative  Proof  from  Glass  on  Paper.  58 

IX.  Positives  on  Collodion   59 

X.  Conversion  of  Negatives  into  Positives   61 

XI.  Albumen  on  glass   63 

Paet  IV. — Positive  Paper   67 

I.  Preparation  of  Paper   67 

II.  Albumenized  Positive  Paper   68 

III.  Printing  the  Proof   69 

IV.  Fixing   70 

V.  New  Process  to  obtain  Positive  Proofs  with  different 

Colors,  and  very  well  fixed   71 

Part  V. — Preparation  of  Chemical  Products   79 

I.  Acetic  Acid   80 

II.  Sulphuric  Acid   81 

III.  Hydrochloric  Acid   81 

IV.  Nitric  Acid   81 

V.  Gallic  Acid   82 

VI.  Pyrogallic  Acid   83 


CONTENTS.  9 

PAGE 

VII.  Ammonia   83 

VIII.  Caustic  Potash   84 

IX.  Iodide  of  Potassium   84 

X.  Iodide  of  Ammonium   85 

XI.  Iodide  of  Silver   85 

XII.  Fluoride  of  Potassium   86 

XIII.  Fluoride  of  Ammonium   86 

XIV.  Cyanide  of  Potassium   86 

XV.  Chloride  of  Sodium   87 

XVI.  Chloride  of  Strontium   87 

XVII.  Chloride  of  Silver   88 

XVIII.  Bichloride  of  Mercury   88 

XIX.  Chloride  of  Gold   89 

XX.  Hydrochlorate  of  Ammonia   89 

XXI.  Bromide  of  Potassium   90 

XXII.  Bromide  of  Ammonium   90 

XXIII.  Bromide  of  Silver   91 

XXIV.  Nitrate  of  Silver   91 

XXV.  Nitrate  of  Zinc   92 

XXVI.  Nitrate  of  Potash  .,   93 

XXVII.  Hyposulphite  of  Soda   93 

XXVIII.  Sulphate  of  Protoxide  of  Iron   93 

XXIX.  Persulphate  of  Iron   94 

XXX.  Hypochlorate  of  Potash   95 

XXXI.  Acetate  of  Ammonia   95 

XXXII.  Acetate  of  Lime   95 

XXXIII.  Acetate  of  Lead   96 

XXXIV.  Ammoniaco-Citrate  of  Iron   96 

XXXV.  Ether   96 

XXXVI.  Alcohol   97 

XXXVII.  Gun-Cotton   97 

XXXVIII.  Pure  Cotton   98 

XXXIX.  Animal  Black   98 

XL.  Starch  and  other  Amylaceous  and  Fatty  Matters 

used  for  Negative  Paper   98 

Part  VI. — The  Apparatus,  Focus,  and  Theory  of  the  Photo- 
graphic Phenomena   101 

The  Apparatus   103 

The  Focus   113 


10 


CONTENTS. 


Theory  of  the  Photographic  Phenomena   117 

To  prepare  Photographs  for  Coloring   129 

Explanations  of  some  of  the  chemical  terms  which  occur  in 
the  present  work   131 

Appendix. — Weights  and  Measures   141 

Avoirdupois  "Weight   141 

Troy  Weight   142 

Kelative  Proportions  between  the  Troy  and  Avoirdupois 

Weights   142 

Apothecaries'  Weight   143 

Dublin  Weights  (Adopted  1850)   143 

French  Metrical  Weights   143 

Value  of  Troy  in  Metrical  Weight   144 

Value  of  Troy  in  Marc  Weight   144 

Wine  or  Apothecaries'  Measure   145 

Imperial  Measure   145 

Value  of  Wine  or  Apothecaries'  Measure  in  Imperial  Measure  146 

Value  of  Imperial  in  Wine  or  Apothecaries'  Measure  146 

French  Measure  of  Capacity — Apothecaries'  Measure   146 

Thermometers   147 

Table  of  the  most  important  Chemical  Elements,  or  Simple 
Bodies,  with  their  respective  Symbols  and  combining 

proportions  148 

Table  of  the  most  important  Chemical  Compounds  (in  a 
Photographic  point  of  view),  with  their  Formulas  and 
combining  proportions   149 

Retail  Price  List   157 

Testimonials  •   160 


INTRODUCTION 


Light  is  one  of  the  most  energetic  causes  of 
chemical  action,  and  a  great  many  combinations 
and  decompositions  can  take  place  only  under  the 
influence  of  light. 

Photography  presents  very  interesting  pheno- 
mena ;  its  results  are  very  great,  but  it  promises 
still  greater  and  more  important  results  for  the 
future.  The  discoveries  made  in  this  science  have 
called  the  attention  of  chemists  to  the  action  of 
light,  and  have  induced  them  to  make  inquiries 
for  the  purpose  of  discovering  the  nature  and 
essentials  of  light. 

The  action  that  light  exercises  upon  the  salts 
of  silver — viz.,  that  from  being  originally  white, 
the  light  transforms  them  to  black- — was  known 
in  the  sixteenth  century,  but  it  was  only  in  the 
eighteenth  century  that  its  mysteries  were  exam- 
ined into.  It  was  at  the  same  epoch  that  the 
influence  of  light  on  salts  of  silver  was  observed, 


12  INTRODUCTION. 

and  Petit  published  some  observations  on  it  in 
1722:  Chaptal  published  his  sixty-six  years  later. 

In  1777,  Sheele  published  the  results  of  his  ob- 
servations on  the  nigrescence  of  chloride  of  silver, 
and  more  particularly  those  alterations  that  the 
chloride  of  silver  suffers  under  the  influence  of 
prismatic  rays.  He  discovered  that  the  chloride 
of  silver,  well  divided  and  spread  on  paper,  would 
turn  black  much  sooner  under  the  influence  of  a 
violet  ray  than  under  any  of  the  other  colors.  In 
1790,  Sennebier  found  that  the  chloride  of  silver, 
under  the  influence  of  the  violet  ray,  became  black 
in  fifteen  minutes  of  exposure,  and  under  the  red 
ray  it  required  twenty  minutes.  In  1801,  Wollas- 
ton  was  engaged  in  the  same  researches,  and  these 
results  led  Wedgwood  into  further  experiments, 
and  to  him  is  due  the  honor  of  having  been  the 
first  photographer. 

In  the  Journal  of  the  Royal  Institution  of  1803 
we  find  a  note  of  Wedgwood's,  with  observations 
by  Davy :  this  paper  is  entitled,  "  Method  of 
Copying  Paintings  upon  Glass,  and  of  making  Pic- 
tures by  the  Agency  of  Light  upon  Nitrate  of 
Silver." 

Here  is  what  Wedgwood  says  (white  paper  cov- 
ered with  nitrate  of  silver  serving  as  an  impression- 


INTRODUCTION. 


13 


able  surface) :  "  The  alteration  of  the  colors  is  in 
proportion  to  the  degree  of  the  intensity  of  the 
light.  In  sunshine,  two  or  three  minutes  will  suf- 
fice to  produce  the  effect ;  in  the  shade,  to  have  the 
same  effect  it  must  remain  some  hours.  The  light 
acts  with  different  degrees  of  intensity  through 
differently  colored  glasses.  If  the  shadow  of  a 
figure  is  thrown  upon  the  prepared  surface,  the 
parts  covered  with  the  shadow  remain  white,  while 
the  other  parts  turn  black.  "When  the  color  is 
fixed  on  paper,  it  proves  fast  to  such  a  degree  that 
water,  and  even  soap  and  water,  fails  to  remove 
it.  Besides  this  method,  there  are  others.  It  will 
be  useful  to  make  copies  of  all  subjects  that  are 
partly  transparent  and  opaque :  natural  objects 
could  be  copied  in  this  manner." 

To  this  Davy  adds :  "  It  has  been  observed 
that  the  image  in  the  camera  obscura  is  too 
weak  to  make  an  impression  upon  nitrate  of  silver 
without  a  reasonable  time."  He  followed  the  ex- 
periments of  Wedgwood,  and  found  that  the  ob- 
jects produced  by  a  solar  microscope  may  be 
copied  on  paper  without  difficulty.  Experiments 
have  proved  that  the  chloride  of  silver  is  more 
sensitive  than  the  nitrate.  The  experiments  made 
some  years  after  have  confirmed  this  fact.  But 

2 


14 


INTRODUCTION. 


though  Wedgwood  and  Davy  obtained  images, 
they  were  ephemeral,  as  they  did  not  know  the 
process  of  making  them  permanent. 

It  was  in  1819  that  Herschel  discovered  the 
property  of  hyposulphite  of  soda,  and  its  deport- 
ment with  salts  of  silver.  In  1812  iodine  was 
unknown,  and  without  these  agents  it  was  impossi- 
ble to  advance  researches. 

In  1814  Niepce  de  St.  Yictor  examined  the 
chemical  effects  of  light.  His  object  was  to  fix 
pictures  obtained  in  the  camera  obscura.  He  dis- 
covered this  property  of  the  solar  rays  to  alter 
various  resinous  matters.  He  spread  a  thin  layer 
of  asphaltum  on>  glass,  and  placed  it  in  the  came- 
ra :  he  left  it  for  six  hours,  and  found  on  the  glass 
a  latent  image,  which  became  visible  in  treating 
the  surface  with  a  solvent.  The  development  of 
the  image  was  made  by  F.  Talbot. 

In  1827  Niepce  made  some  experiments  at 
Kew :  these  pictures  have  some  resemblance  to 
daguerreotypes,  but  they  are  inferior.  Daguerre 
began  his  experiments  in  1824,  and  used  nitrate 
and  chloride  of  silver. 

In  1826  Daguerre  and  Niepce  pursued  their 
experiments  together.  In  1829  Niepce  communi- 
cated his  method  to  Daguerre  in  a  letter,  where  he 


INTRODUCTION. 


15 


says  :  "  My  discovery  that  I  have  named  Heliog- 
raphy,  consists  in  this — that  I  produced  instan- 
taneously the  image  of  the  camera  obscura  in  all 
graduations  from  white  to  black."  He  then  gives 
the  description  of  his  process. 

In  1829  Daguerre  and  Niepce  used  for  the  first 
time  iodine  to  blacken  the  plate  which  contains 
the  image.  Daguerre,  however,  has  observed  some 
peculiarities  on  the  action  of  light  on  the  plate 
treated  in  this  manner.  In  some  of  his  letters  he 
speaks  of  a  decoction  of  cass-weed,  of  phosphorus, 
and  sulphur,  as  acting  on  silver  the  same  as  iodine. 
He  produced  the  same  effect  by  the  oxidation  of 
the  metal. 

In  1833  Niepce  died,  and  six  years  after  Da- 
guerre announced  his  invention.  In  1840  the 
Chamber  of  Deputies  voted  him  an  annual  pen- 
sion of  6000  francs,  and  one  of  4000  francs  to  the 
son  of  Mepce.  On  this  occasion  Arago  stated 
that  this  recompense  was  awarded  for  the  honor  of 
having  presented  the  scientific  and  artistic  world 
with  one  of  the  most  surprising  discoveries,  and 
was  proud  to  present  it.  M.  Duchatel,  Ministre 
de  l'Interieur,  adds :  "  This  discovery  cannot  be 
secured  by  patents  ;  when  it  is  well  known,  every- 
body may  profit  by  it."    Notwithstanding,  we  find 


16 


INTRODUCTION. 


Daguerre  taking  out  a  patent  in  England,  on  thQ 
15th  July,  1839.  Mr.  Berry  obtained  a  patent  for 
a  foreigner  residing  in  France,  on  the  31st  of  Jan- 
uary, 1839.  Talbot  published  some  remarks  on 
the  art  of  Photography,  the  21st  of  February,  the 
same  year.  He  gives  the  process  of  preparing  the 
paper.  Here  we  find  the  same  substances  used  by 
Davy,  and  about  the  same  manipulations  of  this 
chemist. 

The  next  communications  of  importance  were 
those  of  Herschel,  in  1839  and  1840.  This  paper 
is  entitled,  "  The  Chemical  Effects  of  Light  on  the 
Solar  Spectrum."  Herschel  recommends  the  use 
of  the  hyposulphite  of  soda  as  a  fixing  agent ;  and 
in  the  communication  of  1840  he  recommended 
the  use  of  a  hot  solution  of  hyposulphite  of  soda 
in  the  case  of  iodide  of  silver,  this  salt  being  less 
soluble  in  hyposulphite  than  the  chloride.  Her- 
schel also  recommends  to  iodize  the  paper,  by  the 
use  of  iodide  of  potassium  and  nitrate  of  silver. 

At  a  meeting  of  the  British  Association,  in  July, 
1811,  Mr.  Hunt  read  a  paper  with  the  following 
title  :  "  The  Influence  of  the  Ferrocyanide  of  Potas- 
sium upon  the  Iodide  of  Silver,  and  its  extreme 
sensitiveness  in  the  Photographic  Preparations." 
He  gives  also  the  way  to  prepare  the  iodized  paper 


INTRODUCTION. 


17 


as  follows  :  Take  a  sheet  of  good  smooth  paper : 
wash,  it  on  one  side  with  a  solution  of  nitrate  of  sil- 
ver of  one  drachm  dissolved  in  one  ounce  of 
water ;  dry  it,  and  wash  it  again  in  a  solution  of 
two  drachms  of  iodide  of  potassium  to  six  ounces 
of  distilled  water ;  then  wash  it  in  distilled  water, 
and  dry  it  in  the  dark.  Herschel  in  his  paper 
speaks  also  of  the  use  of  the  gallic  acid  as  an 
accelerating  agent,  but  the  proofs  obtained  in  this 
manner  were  negatives.  The  reproduction  of  pic- 
tures was  the  next  point  which  attracted  attention. 
Mr.  Hunt  is  one  of  those  who  were  the  most  suc- 
cessful experimenters.  He  published  a  paper  on 
the  use  of  iodide  of  potassium  as  a  photographic 
agent. 

After  the  process  of  Herschel,  appeared  that  of 
Talbot. 

In  1840  the  art  of  Photography  was  advanced 
by  Goddard  and  Claudet's  discoveries  that  chlorine 
and  bromine,  in  conjunction  with  iodine,  increased 
the  sensitiveness  of  the  plates.  Then  a  large  vari- 
ety of  mixtures  were  recommended. 

One  of  the  most  important  improvements  was 
made  by  Niepce  de  St.  Victor,  nephew  of  I.  Mepce : 
his  process  consisted  in  covering  plates  with  a  thin 
coating  of  albumen  containing  iodine.  This  coat- 
2* 


18  INTRODUCTION. 

ing  takes  pictures  beautifully,  but  it  is  a  little  too 
sensitive  to  take  portraits. 

Le  Gray  was  the  first  to  suggest  the  use  of  the  wax 
paper  for  the  reception  of  negative  images ;  this 
process  gives  very  good  results,  and  is  excelled 
only  by  the  collodion  process. 

The  use  of  collodion  is  recent,  and  it  is  Le  Gray 
who  applied  it  first.  Messrs.  Archer,  Fry,  and  Dia- 
mond, from  London,  had,  about  the  same  time, 
also  made  experiments  with  collodion,  and  now 
this  process  leaves  little  to  be  desired. 

The  entire  domain  of  the  photographic  art  may 
properly  be  divided  into  the  following  sections  : 
I.  Process  on  metallic  plates. 

II.  Process  on  paper. 

III.  Process  on  glass. 

IY.  Process  for  positive  paper 
Y.  Preparation  of  chemical  products. 

YI.  Notions  on  the  phenomena  of  light,  and 
apparatus  used  in  Photography. 


PART  I. 

THE  DAGUERREIAN  PROCESS. 


THE  DAGUERREIM  PROCESS. 


1.  "We  have  very  little  to  say  on  this  process, 
which  now  is  very  well  known;  but  to, have  a 
complete  work,  it  is  necessary  to  speak  of  it  in  as 
brief  a  manner  as  its  importance  will  permit. 

t — Choice  op  Plates. 

2.  The  choice  of  plates  is  very  essential ;  their 
good  qualities  have  a  great  influence  in  the  opera- 
tions. The  best  way  is  to  buy  them  of  a  special 
manufacturer.  In  selecting  a  good  plate,  choose 
such  as  have  a  clean  metallic  aspect,  and  you 
ought  not  to  be  able  to  see  a  trace  of  copper ;  if 
in  the  plate  you  have  some  lines  it  is  nothing  for 
the  execution  of  the  picture,  but  if  you  make  a 
portrait  it  is  much  better  to  place  the  lines  perpen- 
dicular. 


22  PHOTOGRAPHY. 


II. — Polishing  Plates. 

3.  If  the  plate  is  not  well  polished  it  is  impos- 
sible to  have  a  good-  picture :  rotten-stone  and 
rouge  are  the  best  substances  to  use  for  this  pur- 
pose. In  France  they  polish  with  the  hand  ;  here 
they  use  the  apparatus  so  well  known  by  all 
Daguerreotypists. 

4.  The  plate  is  fixed  on  a  small  piece  of  wood ; 
then  pour  on  two  or  three  drops  of  spirits  of 
turpentine;  dust  over  the  plate  a  little  rotten- 
stone,  and  with  cotton  polish  carefully  the  entire 
surface.  After  one  minute  the  plate  is  covered 
with  a  black  dirt ;  remove  it  with  cotton,  and  after- 
wards pour  on  the  plate  some  new  dried  rotten- 
stone,  and  clean  well;  then  pour  on  the  plate 
three  or  four  drops  of  a  mixture  of  turpentine  and 
rectified  alcohol,  and  mixed  with  a  little  rotten- 
stone  ;  leave  it  to  dry ;  then  take  off  the  rotten- 
stone. 

5.  Here  they  use  the  rouge  with  an  apparatus 
to  which  the  foot  gives  a  movement  of  rotation ; 
the  part  with  which  they  polish,  is  of  a  woollen  tex- 
ture covered  with  rouge ;  they  give  the  movement 
of  rotation,  and  pass  the  plate  on  the  wheel.  Be 


THE  DAGUERREIAN  PEOCESS.  23 


sure  that  the  plate  is  well  cleaned ;  breathe  on  the 
surface  of  it,  when  the  white  color  ought  to  disap- 
pear immediately. 

III. — Iodizing  the  Plate. 

6.  In  the  bottom  of  the  iodizing  box  you  have 
some  cotton  covered  with  iodine  ;  on  it  is  a  plate 
of  pasteboard,  which  you  take  care  to  clean  fre- 
quently. x 

The  plate  being  ready,  you  place  it  in  the  iodiz- 
ing box,  and  after  some  time  look  at  the  color ;  if 
it  has  more  color  on  one  side,  turn  the  plate.  To 
see  if  the  color  is  right,  reflect  the  plate  on  white 
paper ;  the  paper  seems  in  the  plate  yellow,  very 
dark,  beginning  to  appear  slightly  pink. 

IY.-— Exposure  to  the  Camera. 

7.  For  this,  see  what  we  say  in  the  part  which 
treats  on  this  subject. 

V. — Exposure  to  Mercury. 

8.  The  mercury  should  be  kept  in  a  dark  room ; 
when  the  proof  is  in  the  box,  warm  the  mercury 


24 


PHOTOGEAPHT. 


with  an  alcohol  lamp  until  the  thermometer  indi- 
cates from  84  to  90  degrees;  then  remove  the 
lamp ;  after  some  minutes  look  through  the  glass 
of  the  box ;  after  four  or  five  minutes  warm  it 
again,  and  remove  the  plate.  It  is  good  sometimes 
to  filter  the  mercury,  to  avoid  the  formation  of  the 
oxide. 


VI. — Washing  with  Hyposulphite  of  Soda. 

9.  Take  a  two-pint  bottle ;  place  in  it  a  funnel 
with  a  filter  ;  place  in  the  filter  about  three  ounces 
60  grains  of  hyposulphite  of  soda  ;  pour  on  water 
until  the  bottle  is  filled.  After  the  plate  comes 
from  the  mercury  box,  wash  it  with  filtered  water, 
then  pour  on  the  filtered  solution  of  hyposulphite ; 
when  all  the  iodide  of  silver  is  dissolved,  wash  the 
plate  well  and  fix  it. 

VII. — Fixing  by  Chloride  op  Gold. 

10.  Fixing  with  chloride  of  gold  is  one  of  the 
best  applications.  This  discovery  is  due  to  M. 
Fizeau.  After  you  have  passed  the  plate  in  the 
solution  of  hyposulphite  of  soda,  and  washed  it, 
place  it  on  the  apparatus  to  fix,  and  pour  on,  a 


THE  DAGUERREIAN  PEOCESS.  25 

solution  of  chloride  of  gold,  of  which  we  indicate 
the  composition  below ;  warm  with  an  alcohol 
lamp.  After  two  or  three  minutes  the  proof  is 
right ;  wash  it  well,  and  dry  it  with  the  alcohol 
lamp. 

11.  Here  is  the  composition  of  the  liquor  of  M. 
Fizeau : 

Dissolve  15  grains  chloride  of  gold  in  a  pound 
of  pure  water,  and  45  grains  of  hyposulphite  of 
soda  in  another  pound  of  water ;  pour  the  solution 
of  gold  in  the  hyposulphite :  use  this  liquor  as  we 
have  indicated. 

But  MM.  Ford os  and  Galis  have  discovered  a 
salt  of  gold,  the  hyposulphite  of  gold  and  soda, 
which  is  much  better  than  the  former;  for  you 
dissolve  15  grains  in  two  pounds  of  water,  and  you 
operate  with  it  as  by  the  process  of  M.  Fizeau. 

12.  We  ought  to  speak  of  the  accelerating  li- 
quors, for  some  of  them  are  very  excellent.  In  all 
of  these  liquors  you  have  iodine  and  bromine,  or 
iodine  and  chlorine.  "We  shall  give  successively 
some  notices  on  the  preparations  of  these  liquids. 

I. — Chloride  of  Iodine 

13.  You  obtain  it  by  the  passage  of  chlorine  gas 

3 


26 


PHOTOGRAPHY. 


in  iodine.  Warm  iodine  a  little  with  an  alcohol 
lamp ;  iodine  becomes  liquid  very  quick.  When 
the  liquid  is  red,  the  operation  is  finished.  It  can 
be  used  by  two  processes :  1.  Pour  two  or  three 
drops  of  this  liquid  in  a  box,  and  expose  the  plate, 
being  covered  with  iodine  (yellow  color),  in  this 
solution ;  when  it  is  pink,  expose  it  in  the  camera. 
2.  Dissolve  some  drops  of  this  liquid  in  water,  and 
put  the  plate  in  the  solution. 

II. — Bromide  of  Iodese. 
Gaudirts  Preparation. 

14.  Take  a  solution  of  iodine  in  alcohol,  pour  in 
bromine  drop  by  drop  until  the  mixture  becomes 
very  red ;  add  water  until  it  becomes  yellow. 

ClaudeVs  Preparation. 

15.  In  a  bottle  containing  about  one  pound  of 
filtered  water,  pour  drop  by  drop  a  solution  of 
iodine  in  alcohol,,  until  the  liquid  has  the  color  of 
a  solution  of  tobacco;  add  then  distilled  water,  sat- 
urated with  bromine,  until  the  liquid  becomes 
clear,  and  has  a  dark-yellow  color ;  then  add  drop 
by  drop  the  solution  of  bromine,  until  the  color  be- 
comes light-yellow. 


THE  DAGTJERREIAN  PROCESS. 


27 


De  ValicourCs  Preparation. 

16.  In  a  bottle  containing  about  four  ounces  of 
water,  pour  30  or  40  drops  of  bromine,  and  after- 
wards add  grain  by  grain  of  iodine  until  bromine 
will  not  dissolve  it.  It  is  very  concentrated;  to 
use  it,  make  the  following  preparation:  pour  15 
grains  in  a  bottle,  and  add  six  or  eight  ounces  of 
water. 

Here  is  the  time  of  the  exposure  of  the  plate  to 
the  bromide  of  iodine : 

For  a  plate  iodized  dark-yellow,    -   25  to  30  seconds. 
"  W     pink       -      -   40  "  50  " 

"  "      pink-violet      -   60  "  70  " 

III. — Chloro-Bromeoe  of  Iodine. 

17.  Take  a  saturated  solution  of  bromine  in  wa- 
ter, pour  on  drop  by  drop  chloride  of  iodine  until 
the  vapors  of  the  bromine  disappear;  add  water 
until  the  solution  becomes  yellow. 

Here  is  the  preparation  of  Baron  Gros :  he  pours 
in  a  bottle  half  a  pound  of  distilled  water,  dissolves 
in  it  300  grains  of  chloride  of  iodine,  agitates  well, 
and  niters.  In  this  liquid,  he  adds  300  other  grains 
of  iodine,  and  agitates  well ;  after  two  hours  he  fil- 


28 


PHOTOGRAPHY. 


ters.  To  this  mixture  he  adds  12  drops  of  bromine 
— the  liquid  is  then  ready. 


LIQUIDS 

Which  are  substituted  for  the  Iodizing  Box. 

18.  There  are  only  three  liquids — Thierry's 
liquid,  the  iodide  of  bromine,  and  the  German 
liquid. 

I. — Thierry's  Liquid. 

19.  The  composition  of  this  liquid  is  unknown, 
but  it  gives  very  good  results.  This  liquid  is  used 
without  water.  In  using  it,  pour  it  in  a  dish ;  you 
must  use  it  all  day.  After  finishing,  be  careful  to 
put  the  remains  in  the  bottle  again.  It  can  be 
used  several  months. 

II. — Iodide  of  Bromine. 

20.  It  is  the  same  as  the  bromide  of  iodine,  only 
we  have  an  excess  of  iodine.  You  prepare  it  in 
the  following  manner :  In  some  bromide  of  iodine, 
with  an  excess  of  bromine,  pour  from  the  solution 
of  iodine  and  alcohol  until  it  precipitates  a  pow- 
der ;  to  use  it,  add  water  until  you  have  the  color 
of  cider. 


THE  DAGUEKREIAN  PEOCESS. 


29 


III. — German  Liquid. 

21.  This  liquid  is  the  chloride  of  iodine  of  M. 
Claudet,  with  water. 

22.  In  the  last  part  of  this  book,  we  shall  speak 
of  the  phenomena  of  light,  and  we  shall  explain 
the  chemical  reactions  which  pass  during  all  op- 
erations. 

3* 


PART  II. 
PROCESS  ON  PAPER. 


* 


PROCESS  ON  PAPER. 


23.  The  processes  on  paper  are  two,  the  dry  and 
the  wet.  The  first  is  generally  practised  to  take 
views ;  the  second  is  preferable  for  pictures.  The 
dry  method  is  very  much  cultivated  now,  for  its 
simplicity  and  its  ready  manipulation  give  to  it  an 
advantage  over  all  other  processes.  There  are  two 
processes  on  dry  paper :  1st,  on  waxed  paper ; 
2d,  on  unwaxed :  these  two  processes  have  the 
same  manipulations  ;  only  on  unwaxed  paper,  when 
all  is  finished,  you  wax  it. 

I. — Process  on  Waxed  Papek. 
Selection  of  Paper. 

24.  The  difficulties  are  very  great  to  procure 
paper  suitable  for  this  purpose  ;  it  must  be  of  a 
good  thickness,  uniform  texture,  well  sized  and 
glazed.  The  manufactories  of  France  and  Eng- 
land give  a  good  paper,  but  we  prefer  the  French ; 


34:  PHOTOGRAPHY. 

but  still  for  positive  proofs  the  Jnglish  is  prefer- 
able. Before  using  the  paper  it  must  be  selected 
sheet  by  sheet  to  see  if  it  is  good ;  if  not,  it  must 
not  be  employed.  We  give  the  names  of  some  of 
the  best  paper  manufacturers  in  England :  Wat- 
man,  Turner,  Nash,  &c.  In  France,  Lacroix, 
Canson,  &c. 

II. — Preparation  of  the  Waxed  Paper. 

25.  Take  a  copper  basin  covered  with  silver,  or, 
if  you  prefer  it,  a  Daguerreotype  plate  ;  this  basin 
should  be  larger  than  the  paper ;  place  it  in  a 
bath  of  boiling  water,  and  put  in  some  white  wax ; 
when  the  wax  is  fused,  lay  upon  it  a  sheet  of  nega- 
tive paper,  and  take  particular  care  not  to  have 
any  air-bubbles ;  and  when  the  paper  is  pene- 
trated by  the  wax,  take  the  sheet  out  and  put  in 
another  one,  and  repeat  the  same  operation  on  all 
sheets;  then  put  the  waxed  paper  between  two 
sheets  of  red  blotting-paper,  and  pass  over  it  a  hot 
smoothing-iron  until  all  the  wax  is  absorbed; 
avoid  leaving  any  wax  on  it :  then  preserve  for 
use  ;  it  is  useful  to  prepare  a  large  quantity,  for  it 
is  a  very  disagreeable  work. 

This  paper  is  very  useful  for  the  photographer : 


PEOCESS  ON  PAPER.  35 

it  is  transparent,  and  permits  yon  to  see  all  air- 
bubbles  ;  it  is  very  tenacious,  and  resists  all  opera- 
tions ;  and  when  the  paper  is  prepared  with  the 
nitrate  of  silver,  you  can  keep  it  many  weeks.  It 
is  much  better  to  buy  this  paper  already  prepared. 


III. — Sensibilization. 

26.  In  this  bath  the  photographer  puts  sugar  of 
milk  and  starch  ;  the  object  is  to  introduce  into  the 
paper  an  organic  matter,  which,  with  the  nitrate 
of  silver,  renders  it  blacker.  Put  in  a  porcelain 
dish — 

Distilled  water  6  pints. 

Eice  9  oz.  160  grs. 

Isinglass  —   300  " 

Boil  until  the  solution  is  reduced  to  three  pints ; 
filter  through  a  clean  cloth.  This  liquid  gives 
body  to  the  paper,  and  yields  very  excellent  tones 
of  black  in  the  proof.    In  two  pints  of  this  liquid 

dissolve — 

Sugar  of  milk    -  -  -  698  grains. 

Iodide  of  potassium  -  225  " 

Cyanide  -  -  -  -  -  121  « 
Fluoride     -  %  " 

When  all  is  dissolved,  filter  it  quickly,  and  keep 


36  PHOTOGRAPHY. 

for  use.  This  bath  is  unalterable.  Before  employ- 
ing it,  filter  it  through  filtering  paper. 

To  operate  with  this  bath  and  the  paper,  put  the 
liquid  in  a  porcelain  dish,  and  immerse  in  it  the 
sheets  of  paper  one  by  one ;  remove  the  air-bub- 
bles, and  leave  it  from  half  an  hour  to  one  hour. 
After  this  take  all  the  paper  in  a  mass,  and  turn 
it ;  then  take  the  sheets,  and,  holding  them  by  the 
corners,  drain  them  for  a  time,  and  then  let  them 
remain. 

The  paper  in  draining  takes  a  violet  tint,  which 
is  very  useful,  as  we  shall  see  in  the  bath  of  sil- 
ver. The  bath  can  be  used  a  long  time,  but  you 
must  filter  it  after  each  operation. 

IV. — Exciting. 

27.  Prepare  the  following  bath  : 

Distilled  water      -  -  -  9  oz.  330  grs. 

Nitrate  of  silver     -  -  -      —  310  " 

Glacial  acetic  acid  -  -  -  —  360  " 
Animal  black        -  —  120  " 

After  the  solution  of  nitrate  of  silver,  acid  acetic 
acid  and  animal  black ;  agitate  it  well,  and  leave 
it  for  some  hours.  Fill  a  porcelain  dish  with  this 
bath,  and  in  another  dish  put  the  distilled  water. 


PROCESS  ON  PAPER. 


31 


Take  the  iodized  paper,  put  it  in,  and  remove 
the  air-bubbles ;  let  it  remain  in  for  six  minutes, 
or,  if  you  prefer  it,  when  your  paper  which  was 
blue  before  becomes  white,  wash  it  well  in  dis- 
tilled water,  and  dry  it  between  blotting-paper ; 
keep  the  water  used  to  wash,  it  is  employed  to 
develop ;  keep  the  paper  out  of  the  light :  all 
these  operations  ought  to  be  performed  by  candle- 
light. You  must  take  particular  care  not  to  touch 
the  paper  with  the  fingers  except  by  the  corners. 
This  paper  will  be  good  during  three  or  four 
weeks,  but  it  is  preferable  to  prepare  it  one  or 
two  days  before  using  it ;  after  you  have  prepared 
ten  sheets,  put  the  nitrate  on  the  animal  black,  and 
then  filter. 

Y. — Exposure. 

28.  For  this,  see  Camera,  in  article  on  Appa- 
ratus. 

YI. — Developing  of  the  Image. 

29.  Take  a  porcelain  dish,  and  put  in  the  follow- 
ing solution : 

4 


38 


PHOTOGRAPHY. 


Distilled  water  1  pint. 

Gallic  acid  30  grains. 

Solution  used  to  wash  the  paper  during  exciting,  1  ounce. 

Immerse  the  proof,  in  this  solution,  and  agitate 
it.  If  the  exposure  has  "been  correct,  the  image 
will  appear  in  15  or  20  minutes ;  sometimes  it  must 
remain  for  some  hours.  As  soon  as  the  image  is 
correct,  remove  it  to  another  porcelain  dish,  full  of 
water,  and  wash  it  well ;  then  fix  it.  If  the  expo- 
sure has  been  too  short,  the  proof  will  be  weak,  and 
not  distinct  in  all  parts.  If  the  exposure  has  been 
too  long,  or  the  light  too  intense,  the  proof  darkens 
in  some  minutes  in  the  bath  of  development.  You 
can  accelerate  the  development  if  you  warm  the 
bath,  but  it  is  dangerous ;  for  the  development,  if 
you  are  not  careful,  will  be  too  rapid. 

VII.— Fixing. 

30.  You  are  obliged  to  fix  the  proof  to  dissolve 
the  iodide  of  silver,  which  has  not  received  the  ac- 
tion of  light ;  the  best  way  is  by  the  hyposulphite 
of  soda. 

Take  rain-water         -      -     1  lb.  10  oz.  100  grs. 
Hyposulphite  of  soda  -      -     —     3  "     60  " 

Pour  this  solution  into  a  dish,  immerse  the  proof, 


PROCESS  ON  PAPER.  39 

and  leave  it  until  all  the  iodide  of  silver  is  dis- 
solved, which  will  take  from  30  to  45  minutes. 
You  will  see  that  the  operation  is  finished  when 
the  dark  spots  are  very  intense,  and  the  light  very- 
brilliant.  When  a  proof  has  been  fixed,  filter  the 
bath  before  you  put  in  another ;  then  wash  it  well 
in  water,  renewed  several  times,  until  it  is  perfectly 
clean,  and  then  dry  it  well. 

If  the  proof  has  lost  its  transparency,  place  it  be- 
tween two  sheets  of  blotting-paper,  and  pass  over 
it  a  smoothing-iron  until  it  renews  its  transparency. 

31.  When  you  operate  on  unwaxed  paper,  all 
operations  are  the  same ;  only  when  all  is  finished 
you  wax  it,  as  we  have  said  in  the  beginning. 

You  could  fix  it  also  with  the  following  bath : 

Water  2  pounds. 

Bromide  of  potassium        -      -372  grains. 

VIII. — Process  on  Wet  Paper. 

32.  This  process  gives  very  fine  results.  The 
paper  is  prepared  in  the  same  manner  as  in  the 
dry  process,  and  may  be  waxed  or  unwaxed. 

(a)  You  immerse  the  paper  in  a  solution  of 
iodide  of  potassium,  thus  formed  : 


PHOTOGRAPHY. 


Distilled  water       -       -     100  parts  (in  weight). 
Iodide  of  potassium  5     "  " 

You  can  leave  it  to  dry,  as  in  the  wax  process. 

(b)  Float  them  upon  the  following  solution : 

Distilled  water    -      -       -     1  lb. 

Nitrate  of  silver  -       -       -     —     1  oz.    15  grs. 

Acetic  acid        -      -      -     —    1  "    120  " 

Leave  them  in  from  eight  to  ten  minutes,  and  use 
immediately. 

(c)  You  have  a  plate  of  glass :  place  upon  it  a 
sheet  of  blotting-paper  dipped  in  clean  water; 
place  upon  it  the  sensitive  paper,  which  has  been 
previously  laid  upon  blotting-paper,  and  then  ex- 
pose it  in  the  camera.  The  action  of  light  is  very 
rapid,  and  it  must  be  exposed  only  about  two-thirds 
of  the  time  of  waxed  paper. 

id)  The  developing  and  fixing  are  the  same  as 
for  the  dry  paper. 

IX. — Process  on  Albumenized  Paper. 

33.  This  process  could  be  substituted  for  the 
waxed  process :  it  gives  very  good  results.  You 
operate  as  follows :  Take  some  white  of  eggs,  and 
add  to  them  10  parts  of  water,  and  for  100  parts  of 


PROCESS  ON  PAPER. 


41 


this  solution  dissolve  five  parts  of  iodide  of  potas- 
sium ;  agitate  it  well,  and  leave  it  12  hours ;  pour 
it  off,  and  put  the  liquid  in  a  porcelain  dish,  placing 
on  it  the  paper ;  leave  it  five  or  six  minutes,  then 
dry  it  well  between  blotting-paper,  and  afterwards 
warm  it  with  a  smoothing-iron.  The  other  opera- 
tions are  the  same  as  for  waxed  paper.  By  this 
process  you  obtain  some  very  fine  proofs,  equally 
as  good  as  by  the  waxed  paper. 

X. — 'Different  Processes. 

34.  At  first  we  ought  to  speak  of  Talbot's  pro- 
cess, for  he  was  the  first  who  ever  practised  it. 

Talbot' 's  Process. 

35.  Take 

Distilled  water  6  ounces. 

Nitrate  of  silver         -       -       -    100  grains. 

Wash  the  paper  with  this  solution,  and  dry  it  well 
near  the  fire  in  a  dark  room.  Afterwards  dip  it  in 
a  solution  of — 

Distilled  water  1  pint. 

Iodide  of  potassium      -       -       -    500  grains. 

Let  it  remain  from  three  to  five  minutes,  and  then 
wash  it  well ;  dry  it  in  blotting-paper,  and  after- 
4* 


42 


PHOTOGRAPHY. 


wards  near  the  fire.  All  other  operations  are  the 
same. 

Bingham? s  Process. 

36.  Take 

Distilled  water  1  ounce. 

Nitrate  of  silver         -       -       -    100  grains. 

Pass  the  paper  in  this  solution,  and  dry  it.  Pass 
it  afterwards  in  a  solution  of — 

Distilled  water  1  ounce. 

Iodide  of  potassium      -       -       -    25  grains. 

Drain  it  well,  wash  it,  and  dry  it  likewise.  Pass 
it  afterwards  in  the  aceto-nitrate  of  silver,  formed 
thus : 

Distilled  water  1  ounce. 

Nitrate  of  silver      -       -      -    50  grains. 
Acetic  acid     -       -       -       -     £  of  the  volume. 

Dry  it  between  blotting-paper,  and  operate  as  we 
have  directed. 

Channing^s  Method. 

37.  Pass  your  paper  in  the  following  solution : 
Distilled  water  1  ounce. 
Nitrate  of  silver    -      -      -       -    60  grains. 

Dry  it,  and  then  pass  it  through  a  solution  of — 
Distilled  water     -      -      -      -     1  ounce. 
Iodide  of  potassium      -      -       -    10  grains. 


PROCESS  ON  PAPER. 


43 


"Wash  it  well  in  water,  and  dry  it  between  blotting- 
paper.  The  paper  is  much  more  sensitive  if  you 
add  to  the  solution — 

Chloride  of  sodium  5  grains. 

CundelVs  Process. 

38.  Pass  your  paper  in  a  solution  composed 
thus : 

Distilled  water  ...  -  1  ounce. 
Nitrate  of  silver   -      -      -      -    17  grains. 

Dry  the  paper  in  the  air  in  a  dark  room,  then  take 
the  following  solution : 

Distilled  water     -    *  -      -       -       1  pint. 
Iodide  of  potassium      -  400  grains. 

Common  salt       -      -      -      -    100  " 

Pass  the  paper  in  this  solution.  The  side  which 
has  received  the  nitrate  of  silver  leave  to  dry. 

Martin's  Method. 

39.  For  negatives : 

(a)  Distilled  water  20  ounces. 

Iodide  of  potassium       -      -      -      -     1  " 
Cyanide  of  potass,  (concentrated  solution)  20  drops. 

(b)  Nitrate  of  silver  -      -      -  1  oz.  6  drachms. 
Distilled  water    -    (  -      -      -   20  " 

Glacial  acetic  acid      -      -  \  u 


44  PHOTOGRAPHY. 

Apply  the  solution  dry  it,  and  pass  it  after- 
wards in  the  solution  (b)  and  dry  immediately. 

(c)  Solution  of  concentrated  gallic  acid. 

(d)  Alcohol. 

(e)  Kain- water       -      -      -      -20  ounces. 
Hyposulphite  of  soda        -  2  " 

For  positives : 

(a)  Distilled  water  20  ounces. 
Chloride  of  sodium         -       -    336  grains. 

(b)  Distiiled  water       -      -  20  ounces. 
Nitrate  of  silver      -      -      -      2  " 

(c)  Eain-water     -      -      -      -     20  ounces. 
Hyposulphite  of  soda  2  " 

To  this  solution  you  add  60  grains  of  nitrate  of  sil- 
ver, dissolved  in  one  ounce  of  water. 

Jordaris  Method. 

40.  Take  iodide  of  silver  recently  precipitated, 
and  dissolve  it  in  iodide  of  potassium. 

Apply  this  solution  to  the  paper ;  dry  it  well, 
and  place  it  upon  clean  water ;  it  is  then  ready  for 
use. 

Thomas's  Method. 

41.  Prepare  the  following  bath  : 


PROCESS  ON  PAPER. 


45 


Ioidide  of  potassium  (concentrated  solution)  2|  drachms. 


Bromide  of  potassium     -      -      -  10  grains. 

Mix  and  filter  it  in  a  porcelain  dish  ;  place  a  sheet 
of  paper  on  this  bath,  and  leave  it  two  minutes ; 
hang  it  up  carefully  by  a  corner  to  drain. 

42.  The  following  is  the  bath  to  excite : 

Distilled  water    -       -  -    7  ounces. 

Nitrate  of  silver  -    5  drachms. 

Acetic  acid        -      -      -      -    9  " 

After  this,  proceed  exactly  the  same  as  in  the 
wet  method. 

XL — Negative  Method  with  Albumen. 

43.  Take  the  white  of  ten  eggs,  and  dissolve 
in  it — 

Iodide  of  ammonium  60  grains. 

Bromide  8     "  ■ 

Chloride  of  sodium         -      -      -       8  " 

Agitate  it  well,  and  let  it  remain  one  night.  Use 
this  solution  as  we  have  indicated. 


Pure  iodine 


9  grains. 


Dissolve  it,  and  add — 

DiUlled  water 
Iodide  of  potassium 


11^  ounces. 
4  drachms. 


46 


PHOTOGRAPHY, 


XIL — Preparation  op  a  Special  Paper  for 
Portraits. 

44.  In  a  bottle  make  the  following  solution : 

Distilled  water  -  6 '200  grains. 
Iodjde  of  potassium    -  3*10  " 

Cyanide   31  " 

Fluoride    -----     8  " 

Put  this  solution  in  a  porcelain  dish,  and  float  the 
paper  upon  it ;  let  it  remain  two  or  three  minutes, 
and  then  dry  it  between  blotting-paper ;  pass  it 
afterwards  into  the  bath  of  aceto-nitrate  of  silver, 
and  leave  it  ten  or  fifteen  minutes,  and  then  ope- 
rate immediately  with  it. 


XIII. — Negative  Paper  with  Gelatine. 

45.  In  two  pounds  of  distilled  water  dissolve  j 
380  grains  of  gelatine  ;  of  this  solution,  take  566 
grains,  and  to  it  add — 

Iodide  of  potassium      -  202  grains. 

Bromide      -      -  -      -      62  " 

Chloride  of  sodium      -      -      -       31  " 

Pass  it  through  a  linen  cloth,  and  immediately 
immerse  your  paper  in  it ;  let  it  remain  in  for  fif- 


PROCESS  ON  PAPER. 


47 


teen  minutes,  and  then  hang  it  np  to  drain ;  and 
when  dry,  operate  the  same  as  on  the  wet  paper. 

XIY. — Negative  Paper  with  Alcohol. 


i. 

46.  Commercial  Alcohol  2  lbs.  4  oz. 

Collodion   155  grains 

Iodide  of  potassium  -  -  -  155  " 
Cyanide  of  potassium    -  15|  " 

II. 

Alcohol   2  lbs.  4  oz. 

Camphor   233  grains. 

Varnish  gum-lac  with  alcohol       -       78  " 

Iodide  of  potassium  -  124  " 
Fluoride  of  potassium  -  -  -  31  " 
Cyanide  of  potassium    -       -       -       31  " 


Pass  yonr  paper  in  this  bath  ;  dry  it  thoroughly  ; 
and  afterwards  operate  exactly  the  same  as  we 
have  said  before,  when  speaking  of  the  waxed 
paper. 

XT. — Negative  Paper  with  the  Ammoniaco- 
Citrate  of  Iron. 

47.  Put  the  sheet  of  paper — one  side  only — on 
the  ammoniaco-citrate  of  iron  (see  §  107) ;  dry  it 


48 


PHOTOGRAPHY. 


thoroughly  in  a  dark  room ;  it  is  then  ready  to 
expose  to  the  light ;  it  is  very  sensitive  ;  but  it  is 
much  better  to  add  some  nitrate  of  silver,  and  to 
use  the  following  formula  : 

Water  saturated  with  aminoniaco-citrate 

of  iron    -      -      -       -      - '     -  1550  grains. 

Distilled  water      -       -       -      -      -  1550  " 

Nitrate  of  silver  31  " 


PART  III. 

PEOCESS  ON  GLASS. 


r 


PROCESS  ON  GLASS. 


I. — Collodion. 
Cleaning  the  Glass, 

48.  Place  the  glass  plate  on  a  quire  of  tissue- 
paper  ;  pour  some  alcohol,  in  which  tripoli  powder 
is  suspended  with  a  little  ammonia.  Here  is  the 
composition  : 

Alcohol    -       -  -       -    3100  grains. 

Ammonia        -  155  " 

Eotten-stone     -      -      -      -      78  " 

Rub  every  part  of  the  glass  with  tissue-paper  on 
both  sides,  and  dry  it  well  with  another  sheet  of 
paper ;  after  which  carefully  polish  it  with  a  clean 
wash  (chamois)  leather  ;  clean  the  glass  just  before 
using  it. 

II. — Pkepakation  of  Collodion. 

49.  We  recommend  a  large  bottle  of  collodion 


52 


PHOTOGRAPHY. 


to  be  kept  on  hand,  unless  to  those  who  can  readily 
procure  a  good  article,  as  it  will  settle  the  better, 
and  there  need  be  no  fear  of  its  not  keeping. 

Here  is  the  fonnula  which  we  employ,  and 
which  has  always  succeeded  well  in  our  hands. 

In  a  ground  stoppered  bottle  you  introduce — 

Kectified  ether    -  -  1000  parts  (weight). 

Commercial  alcohol  -  200    "  M 

Gun-cotton        -  -  20  or  40*  parts  (weight). 

Aqua  ammonia    -  -  50  drops. 

Agitate  occasionally,  and  when  the  cotton  is  dis- 
solved, add — 

Iodide  of  ammonium     -      -     10  parts  (weight) 
Cyanide  of  potassium    -      -      1    "  " 
Fluoride  of  potassium  1    "  K 

When  the  salts  are  dissolved,  filter  through  a  cot- 
ton cloth  into  a  bottle  previously  washed  with 
ether.  You  can  substitute  for  the  iodide  of  am- 
monium— 

Iodide  of  potassium      -      •     10  parts  (weight). 
Iodine  2    "  " 

The  collodion  has  a  yellow  color,  which  after  a 
few  days  becomes  a  light  straw-color. 


*  In  winter  40,  in  summer  20. 


PROCESS  ON  GLASS. 


53 


50.  As  the  solution  of  the  salts  in  ether  and 
alcohol  is  more  difficult,  dissolve  the  salts  in  a 
few  drops  of  water,  and  then  add  to  the  collodion. 
For  immediate  use,  keep  it  in  small  bottles  of  three 
or  four  ounces  each. 

III. — Application. 

51.  Take  the  glass  in  the  left  hand  by  the  cor- 
ner, and  with  the  right  hand  pour  the  collodion  in 
the  centre  of  the  glass ;  flow  the  collodion  over  the 
glass  by  a  half-rotary  motion.  When  the  whole 
surface  of  the  glass  is  covered,  pour  off  the  excess 
of  collodion  by  the  opposite  corner,  to  prevent 
streaks ;  you  must  only  pour  upon  the  glass  suffi- 
cient collodion  to  cover  it.  You  place  it  horizon- 
tally, and  you  give  it  a  gentle  inclining  motion 
from  side  to  side.  When  the  collodion  begins  to 
dry,  immerse  it  in  the  sensitive  bath. 

IV. — Sensitive  Bath. 

52.  You  prepare  the  silver  bath  in  the  following 
manner : 

Distilled  water    -  1000  parts  (weight). 

Nitrate  of  silver  80    14  " 

5* 


54: 


PHOTOGRAPHY. 


You  dissolve  the  whole  of  the  silver  in  distilled 
water,  and  yon  then  filter  it,  and  let  it  repose  for 
some  honrs.  For  this  purpose  yon  must  use  a  ver- 
tical bath  of  glass  or  gntta-percha. 

Before  nsing  the  bath,  filter  yonr  solution  ;  when 
the  bath  is  nearly  full,  yon  immerse  the  plate 
quickly  ;  raise  it  after  one  minute  to  inspect  it ;  it 
has  a  milky  appearance,  nearly  white  ;  it  has  also 
an  oily  appearance,  which  is  caused  by  the  ether. 

When  these  phenomena  have  disappeared,  and 
the  glass  has  not  the  marble  appearance,  you  re- 
move it:  allow  it  to  drain,  and  then  put  it  in 
the  frame. 

The  length  of  time  to  remain  in  the  bath  of  sil- 
ver varies  from  one  to  three  minutes.  After  you 
have  prepared  from  five  to  six  plates  in  this  bath, 
you  filter  it,  and  from  time  to  time  add  a  small 
quantity  of  nitrate  of  silver. 

V. — Exposure  in  the  Camera. 

53.  "We  cannot  recommend  this  collodion  as  the 
quickest,  but  its  success  is  sure ;  the  exposure 
varies  according  to  the  distance  and  the  quantity  of 
light  that  you  have  during  the  experiment.  With 
the  object-glass  of  18  inches,  it  must  remain  from 


PEOCESS  ON  GLASS.  55 

one  to  ten  seconds  for  views,  and  from  30  to  40 
seconds  for  a  portrait  in  the  shade. 

VI. — Developing. 

54.  There  are  two  ways  to  develop : 

(a)  By  pyrogallic  acid. 

(5)  By  protosnlphate  of  iron. 

(a)  Developing  by  pyrogallic  acid,  prepare  the 
following  bath : 

Distilled  water      -      -      100  parts  (in  weight). 
Pyrogallic  acid      -  1      "  u 

Glacial  acetic  acid  -  10      "  " 

When  the  plate  is  removed  from  the  frame,  you 
take  it  by  one  corner ;  cover  it  with  the  former 
solution ;  agitate  well  the  fluid  over  the  entire  sur- 
face, being  careful  that  the  plate  is  entirely  covered 
with  the  liquid.  The  image  gradually  appears, 
but  it  is  not  very  distinct ;  you  render  it  perfect  by 
putting  it  in  a  bath  of — 

Nitrate  of  silver  1  part  (weight). 

Distilled  water      -      -      -   100    "  " 

When  you  have  attained  the  degree  of  develop- 


56 


PHOTO  GE  APHY . 


merit  wished  for,  you  remove  it,  and  wash,  it  with 
distilled  water,  and  then  fix  it.  This  development 
is  preferable  when  the  picture  receives  a  uniform 
light,  and  the  contrasts  of  light  and  shade  are  per- 


(b)  Developing  by  protosulphate  of  iron,  you 
prepare  the  following  bath : 


You  pour  this  filtered  substance  in  a  porcelain 
dish,  and  plunge  the  proof  in  immediately ;  in  three 
or  four  seconds  the  image  appears,  and  is  perfect 
in  every  part.  If  it  has  a  gray  tint,  the  exposition 
in  the  camera  has  been  too  long ;  if  the  light  parts 
become  black,  it  is  the  contrary.  If  the  proof  has 
a  color  too  light  and  too  uniform,  you  could  give 
it  more  vigorous  tones  by  plunging  it  into  a  bath 
of  gallic  acid,  containing  a  little  aceto-nitrate  of 
silver.  You  first  drain  the  proof,  then  wash  and 
fix  it.  This  bath  can  be  used  a  great  number  of 
times,  if  you  filter  it  carefully  after  using  it. 


feet. 


Distilled  water  - 
Protosulphate  of  iron  - 
Glacial  acetic  acid 
Sulphuric  acid 


1000  parts  (weight). 
100   "  " 
20   u  " 
20  drops. 


PROCESS  ON  GLASS. 


57 


VII. — Fixing  the  Peoof. 

55.  There  are  two  methods  to  fix  the  proof: 

(a)  By  sulphate  of  peroxide  of  iron. 

(b)  By  hyposulphite  of  soda. 

{a)  Fixing  by  the  sulphate  of  peroxide  of  iron, 
prepare  the  following  bath  : 

Distilled  water    -  1000  parts  (weight), 

Sulphate  of  peroxide  of  iron  -       2   44  44 

Wash  the  proof,  and  cover  it  with  the  former  solu- 
tion ;  allow  it  to  remain  in  this  solution  from  fifty 
seconds  to  one  minute,  and  then  wash  it  with  fil- 
tered water ;  afterwards  with  distilled  water ;  and 
then  dry  it ;  and  finish  drying  it  before  a  gentle 
fire. 

(5)  Fixing  by  hyposulphite  of  soda : 

Distilled  water    -      -      -   1000  parts  (weight). 
Hyposulphite  of  soda   -      -      6  0    4  4  44 

56.  You  operate  as  with  the  sulphate  of  per- 
oxide of  iron.  This  process  renders  collodion  less 
firm  than  before. 

Sulphate  of  peroxide  of  iron  leaves  a  yellow 
opaque  tint,  which  is  very  good  for  a  faint  proof. 


58  PHOTOGRAPHY. 

You  can  also  fix  a  weak  proof  with  a  solu- 
tion of— 

Distilled  water    -  -      -   1000  parts  (weight). 

Bromide  of  potassium  -      -      50    "  " 

YIII. — To  Transfer  the  Negative  Proof  from 
Glass  on  Paper. 

57.  Take  the  proof,  well  fixed,  put  it  in  a  bath 
of  water  with  a  little  acetic  acid,  and  let  it  remain 
until  the  collodion  rises  from  the  corners  of  the 
glass ;  then  submit  it  to  a  very  gentle  current  of 
water,  and  continue  it  until  the  water  passes  under 
the  collodion.  Take  two  sheets  of  paper,  put  them 
in  water,  and  afterwards  between  iwo  sheets  of 
blotting-paper,  and  then  cover  them  carefully  with 
dextrine ;  take  one  sheet  and  extend  it  on  the 
proof,  then  the  paper  is  adherent  to  the  collodion. 
Take  another  glass  larger  than  the  proof,  and  apply 
it  on  a  sheet  of  paper ;  turn  the  two  glasses,  and 
take  out  that  which  has  the  proof ;  the  collodion 
then  is  adherent  to  the  paper,  but  you  see  some 
undulations.  To  remove  the  undulations,  take  the 
second  sheet  of  paper,  and  apply  the  side  passed  to 
the  dextrine  on  the  proof,  which  is  then  between 
the  two  sheets.    Then  put  some  blotting-paper  on 


PEOCESS  ON  GLASS. 


59 


the  last  sheet  of  paper,  strike  with  the  hand,  and 
press  ont  the  excess  of  dextrine  ;  then  take  the 
proof  and  dry  it  well.  Wax  the  proof  by  the  ordi- 
nary process,  and  you  will  then  have  excellent  pos- 
itive pictures. 

IX. — Positives  on  Collodion. 

58.  The  principal  advantage  positive  pictures 
possess  is,  that  they  do  not  reflect  like  the  silver- 
plate  pictures,  and  they  require  less  time  to  take 
them  than  negative  pictures.  The  preparation  of 
the  plate  for  positives  is  precisely  the  same  as  for 
negatives,  except  a  much  shorter  exposure  in  the 
camera.  The  pictures  are  developed  with  pyro- 
gallic  acid,  to  which  is  added  a  drop  or  two  of  nitric 
acid ;  or  with  the  protosulphate  of  iron,  and  the  same 
quantity  of  nitric  acid.    Make  the  solution  thus : 

Pyrogallic  acid     -       -       -       -  10  grains. 

Acetic  acid  -       -       -       -  65  minims. 

Nitric  acid  1  u 

Distilled  water     -      -      -      -  10  ounces. 

This  is  to  be  carefully  filtered.    Or  thus  : 

Protosulphate  of  iron         -      -  26  grains. 

Acetic  acid  80  minims. 
Nitric  acid        ....       2  u 

Distilled  water   -      -      -      -  640  " 


60 


PHOTOGRAPHY. 


These  developing  solutions  are  so  energetic,  that 
every  one  who  follows  the  directions  of  the  books 
heretofore  published,  is  extremely  annoyed  by  the 
unequal  action  upon  the  surface  of  the  plate,  where 
the  liquid  first  falls  in  pouring  it  over.  The  plan 
also  of  immersing  in  a  vertical  bath  has,  to  a  great 
extent,  the  same  objection,  with  the  greater  one  of 
preventing  the  judgment  and  taste  of  the  operator 
from  being  exercised.  To  avoid  this,  we  recom- 
mend that  a  glass  dipper  (of  our  style  of  make)  be 
bent  at  a  right  angle,  so  that  the  handle  and  the 
hooks  are  perpendicular;  lay  on  your  plate,  and 
quickly  immerse  it  in  a  shallow  bath,  only  suffi- 
ciently deep  to  cover  the  surface,  and  no  more. 
This  plan  enables  the  operator  to  scrutinize  the  de- 
velopment as  it  takes  place.  It  leaves  him  also 
with  free  and  clean  hands,  which  is  both  desirable 
and  more  comfortable.  When  the  image  is  devel- 
oped to  your  liking,  remove  it  by  means  of  the  dip- 
per, and  immerse  it  in  a  bath  of  clean  water,  deep 
enough  to  cover  the  whole  surface,  and  wash  it  well 
by  frequently  raising  and  depressing  it  with  a  gen- 
tle churning  motion.  In  this  manner  the  most  fra- 
gile film  of  collodion  will  be  removed  unbroken. 
If  the  picture  develops  slowly,  it  has  not  been  long 
enough  exposed  in  the  camera,  and  vice  versa. 


PROCESS  ON  GLASS. 


61 


When  your  negative  plate  is  dry,  the  last  and 
finishing  stroke  is  to  protect  it  from  dust  and  in- 
jury. This  is  best  accomplished  by  varnishing  it. 
The  best  varnish  for  this  purpose  is  the  amber  var- 
nish. This  must  be  quickly  flowed  over  the  surface, 
in  the  same  manner  as  described  in  flowing  collo- 
dion, but  it  must  be  poured  off  again  immediately. 
The  solvent  is  so  exceedingly  volatile  that  it  sets 
almost  immediately.  A  second  coat  may  be  ap- 
plied if  desired ;  this  enables  the  operator  to  wash 
or  clean  the  negative  plate  at  pleasure. 


X. — Conversion  of  Negatives  into  Positives. 

59.  Sir  John  Herschel  suggested  that  the  glass 
be  smoked  on  the  collodion  side,  backing  the  proof 
with  black  varnish,  paper,  velvet,  cloth,  or  any  other 
black  substance.  Another  method  is  to  obtain  the 
picture  by  the  ordinary  process,  that  is,  by  collo- 
dion, and  then  developing  by  proto-nitrate  of  iron. 
After  the  picture  is  properly  developed,  pom'  over 
the  plate,  gently  warmed,  a  solution  of  pyrogallic 
acid  and  partially  decomposed  hyposulphite  of 
soda — definite  proportions  are  unnecessary.  The 
formation  of  metallic  silver  on  the  darkened  parts 
renders  them  perfectly  white  and  lustrous.  The 
6 


62 


PHOTOGRAPHY. 


velvet  backing  relieves  the  picture  of  that  reflect- 
ing property  which  is  so  objectionable  in  Daguer- 
reotypes. A  solution  of  bichloride  of  mercury,  or 
one  of  proto-nitrate  of  iron  and  pyrogallic  acid 
combined,  poured  over  the  proof,  will  also  produce 
gratifying  results. 

Probably  the  most  satisfactory  method  is  to  use 
silver  combined  with  iodized  collodion.  Cover  the 
glass  plate  with  the  collodion,  and  immediately  be- 
fore it  becomes  dry  immerse  it  in  the  following 
bath : 

Nitrate  of  silver  34  grains. 

Nitric  acid  -  -  -  -  21  " 
Distilled  water  -      -      -      -   410  " 

The  developing  is  done  with  the  sulphate  of  pro- 
toxide of  iron,  and  washed  with  particular  care,  as 
directed  elsewhere  in  this  work. 

By  this  proceeding,  thus  far  we  have  only  a  neg- 
ative picture.  The  finishing  stroke  is  to  immerse 
it  in  the  following  bath,  to  possess  a  beautiful  and 
brilliant  positive : 

Distilled  water  -  -  -  -  17  ounces. 
Cyanuret  of  potassium  -  -  -  189  grains. 
Nitrate  of  silver    -      -      -  81  " 


PROCESS  ON  GLASS. 


63 


XI. — Albumen  on  Glass. 

60.  Take  the 

White  of  eggs      -  1550  grains. 

Iodide  of  ammonium   -      -      -      W }  " 

Agitate  it  well  and  let  it  remain  twelve  hours,  ana 
then  decant  it.  Clean  your  glass  well,  and  apply 
the  albumen  the  same  as  the  collodion.  Dry  it  in 
a  small  box,  so  as  to  keep  it  free  from  dust,  &c, 
and  then  pass  it  into  the  bath  of  nitrate  of  silver, 
composed  in  the  following  manner : 

Distilled  water    -  4650  grains. 

Nitrate  of  silver  -  -  -  -  372  " 
Acetic  acid         -  465  " 

Let  it  remain  for  two  or  three  minutes,  wash  it  well, 
and  dry  it  in  a  dark  room.  You  must  develop  with 
a  warm  bath  of  gallic  acid,  containing  one-tenth  in 
volume  of  aceto-nitrate  of  silver.  However,  it  is 
equally  as  good,  if  not  better,  to  develop  with  the 
protosulphate  of  iron  in  the  same  proportions  as 
we  indicated  for  the  collodion. 


PART  IV. 

POSITIVE  PAPER. 


I 


POSITIVE  PAPER. 


I. — Preparation  of  Paper. 

61.  Prepare  the  two  following  solutions : 
(a)  Chloride  of  ammonium       -     —    75  grains. 
Distilled  water   -      -      -     3  oz.  60  " 

Pour  this  solution  into  a  porcelain  dish. 

(5)  Nitrate  of  silver  -  —  280  grains. 

Distilled  water   -      -      -     3  oz.  60  " 

Pour  this  solution  into  another  dish  similar  to  the 
former.  Use  thick  paper,  which  you  must  cut  to 
the  size  of  your  dishes.  Place  one  side  only  of  the 
paper  in  the  bath  {a\  and  leave  it  for  two  or  three 
minutes ;  dry  it  well  between  sheets  of  blotting- 
paper.  Prepare  three  sheets  before  you  commence 
to  place  them  in  the  bath  of  nitrate. 

Take  the  first  sheet  of  paper,  clean  it  well,  and 
place  it  in  the  bath  (5),  and  leave  it  in  from  three 
to  five  minutes  ;  if  you  leave  it  in  a  short  time,  you 
have  your  paper  of  a  red  color ;  on  the  contrary,  if 
you  leave  it  in  a  long  time,  the  color  is  black. 
Afterwards  dry  it  well  between  sheets  of  blotting- 


68  PHOTOGEAPHT. 

paper.  It  is  the  best  way  to  prepare  your  paper 
the  day  before  using  it,  and,  when  going  to  use  it, 
dry  it  well  before  a  gentle  fire. 

When  the  weather  is  bad,  you  can  use  the  nega- 
tive paper,  not  waxed  or  dried  for  positives.  Then 
you  can  develop  with  gallic  acid.  Fix  with  the 
hyposulphite  of  soda,  for  positive  pictures.  The 
picture  is  then  slightly  red ;  you  can  make  it  black 
by  passing  it  through  the  following  bath : 

Water   2  lbs. 

Chloride  of  gold      -      -      -      -      15  grains. 
Hydrochloric  acid    -  375  " 


II. — Albumenized  Positive  Paper. 

62.  Take  white  of  eggs      -  3  oz.  60  grains. 

Chloride  of  sodium     -      -      —   60  " 

Agitate  it  well ;  leave  it  one  night,  and  then  de- 
cant it.  Pour  this  liquid  into  a  porcelain  dish,  and 
prepare  the  positive  paper  as  we  have  before  indi- 
cated for  negative  paper ;  leave  it  in  three  or  four 
minutes,  and  then  dry  it  with  a  smoothing-iron. 

Pass  this  paper  through  the  following  bath  of 
nitrate  of  silver : 

Distilled  water    -      -      -      -   3  oz.  60  grains, 
Nitrate  of  silver  -      -      -      - '  -  240  " 

Leave  it  in  from  four  to  five  minutes.   Dry  it  in 


POSITIVE  PAPER. 


69 


the  same  manner  as  we  have  said  for  the  ordinary 
positive  paper. 

III. — Peinting  the  Peoof. 

63.  Take  your  negative :  place  it  on  a  glass 
of  the  frame  to  reproduce ;  place  on  a  sheet  of 
positive  paper,  the  side  which  has  been  prepared 
of  the  negative;  over  all  place  a  sheet  of  black 
paper,  and  the  second  glass  of  the  frame  ;  shut  the 
frame,  and  leave  a  corner  of  the  positive  paper 
free,  so  as  to  see  when  all  is  finished. 

Another  printing  process  is  performed  in  the 
following  manner :  Lay  several  folds  of  cotton  flan- 
nel on  the  smooth  surface  of  the  ordinary  printing 
machine  (used  here) ;  then  on  it  the  sensitive  paper, 
over  which  the  collodion  negative,  held  down  by 
the  springs,  and  expose  to  the  rays  of  the  sun.  The 
hinge  permits  a  ready  inspection  of  the  effect  upon 
the  paper. 

The  following  are  the  colors  which  the  paper 
takes :  Gray-blue,  neutral  color,  violet-blue,  blue- 
black,  black,  black  sienna,  sienna,  colored  sepia, 
yellow  sepia,  yellow  dead-leaves,  and  gray,  until 
the  oxide  of  silver  becomes  of  a  metallic  substance ; 
then  you  must  stop. 


TO 


PHOTOGRAPHY. 


64.  If  you  wish  to  have  a  black  proof,  after  the 
fixing  by  hyposulphite  of  soda  it  is  necessary  that 
the  dark  parts  have  the  sepia  color,  and  the  white 
parts  the  grayish-blue  color ;  it  is  exceedingly  dif- 
ficult to  fix  the  time  of  exposure. 

1Y. — Fixing. 

65.  Prepare  the  following  bath  : 

Filtered  water     -      -  1  lb.  2  oz.  360  grs. 

Hyposulphite  of  soda    -      -      —  3  "     60  " 

Dissolve  in  it  225  grains  of  chloride  of  silver,  that 
you  have  precipitated  from  a  solution  of  nitrate, 
and  agitate  it  well.  The  older  this  hath  is,  the 
tetter.  You  must  not  reject  the  black  deposit 
which  is  in  this  bath;  decant  the  x  clear  liquid, 
and,  when  all  is  finished,  pour  the  liquor  on  the 
deposit. 

With  this  bath  you  can  obtain  all  colors  from 
red  to  black,  and  yellow ;  you  must  leave  a  proof  at 
least  one  hour ;  sometimes  it  is  necessary  to  be  left 
three  or  four  days. 

66.  You  have  the  sienna  color  by  adding  to  this 
bath  one  ounce  of  ammonia.  You  have  colors 
very  soft  and  yellow,  if,  after  the  fixing,  you  wash 


POSITIVE  PAPEE. 


71 


the  proof,  and  pass  it  through  a  solution  composed 
of— 

Distilled  water  2  pints. 

Hydrochloric  acid  1  ounce. 

When  your  proof  is  right,  wash  it  well  during 
some  hours ;  you  must  leave  it  in  water  until  this 
liquid  has  no  sweet  taste.  You  can  fix  a  great 
many  proofs  in  the  same  bath. 


V. — New  Process  to  obtain  Positive  Proofs  with 
Different  Colors,  and  vert  well  fixed. 

67.  Not  long  since,  amateurs  lamented  to  see 
the  finest  proofs  blot,  and  sometimes  to  disappear 
entirely.  When  a  proof  is  not  solid,  it  is  caused 
by  the  use  of  old  hyposulphite  of  soda,  which  con- 
tains too  much  salts  of  silver.  A  positive  proof 
can  disappear  in  two  ways.  1st.  Because  it  con- 
tains some  salts  of  silver.  2d.  Because  it  contains 
sulphur  or  hyposulphite  of  soda. 

The  first  accident  is  produced,  1st,  by  a  too  short 
time  with  the  hyposulphite  of  soda;  thus  some 
chloride  of  silver  remains  in  the  paper,  and  so 
causes  the  proof  to  become  black.  2d.  By  the  use 
of  hyposulphite  of  soda  which  contains  too  much 


72 


PHOTOGRAPHY. 


salts  of  silver :  the  hyposulphite  of  soda  cannot  dis- 
solve the  chloride  of  silver,  which  forms  a  double 
salt  with  the  hyposulphite ;  and  consequently  it 
remains  in  the  paper. 

The  second  accident  is  produced,  1st,  by  the  ad- 
dition of  an  acid  to  the  hyposulphite  of  soda,  which 
is  decomposed,  and  thus  the  sulphur  is  freed. 
2d.  By  the  immersion  of  too  many  proofs  in  the 
same  bath,  the  quantity  of  chloride  and  nitrate  of 
silver  which  is  in  these  proofs  is  too  considerable, 
— you  have  a  disengagement  of  nitric  acid ;  the 
bath  is  decomposed,  and  you  have  a  precipitation 
of  sulphur. 

68.  When  a  proof  is  out  of  the  solution  of  hypo- 
sulphite of  soda,  if  you  do  not  wash  it  well  the 
proof  will  still  contain  some  of  this  salt,  and  the 
image  will  in  consequence  disappear. 

By  this  we  know  that  if  a  proof  disappears,  it  is 
because  it  contains  some  salts  of  silver  or  hyposul- 
phite. 

To  dissolve  chloride  of  silver,  it  is  preferable  to 
use  a  bath  of  hyposulphite  of  soda  and  liquid  am- 
monia, as  in  our  opinion  they  are  the  best  sub- 
stances you  can  use. 

69.  The  sulphuret  of  carbon  and  alcohol  dissolve 
the  sulphur ;  they  ought  to  be  used  for  the  proofs. 


positive  paper.  73 

The  hyposulphite,  with  the  nitrate  of  silver,  gives 
a  black  precipitation  of  sulphuret  of  sil  ver  :  before 
using  this  bath,  you  must  transform  all  the  nitrate 
of  silver  into  chloride ;  and  for  that  purpose  you 
can  pass  the  proof  into  a  bath  of  water  containing 
some  chloride  of  sodium,  and  afterwards  wash  it 
perfectly  clean. 

70.  A  positive  proof  ought  to  be  exposed  to  the 
light  a  sufficient  time  to  remain  one  hour  at  least 
in  the  hyposulphite  ;  this  way  of  fixing  generally 
gives  a  violet  or  red  color.  It  must  afterwards  be 
washed  at  least  four  hours,  changing  the  water 
every  hour.  If  you  wish  a  proof  solid,  dry  it  be- 
tween blotting-paper,  and  wash  it  with  alcohol. 
When  you  use  old  hyposulphite,  you  must  remove 
the  proof  before  you  have  the  color  that  you  wish ; 
pass  it  in  water  for  some  minutes,  and  then  in  a 
new  bath  of  hyposulphite.  If  you  wish  a  good 
proof,  it  is  very  bad  to  add  any  acid  to  the  hypo- 
sulphite, which  gives  a  disengagement  of  sulphur- 
ous acid. 

If  you  use  this  process,  after  you  have  washed 
once  you  must  treat  the  proof  with  alcohol,  which 
contains  half  of  sulphuret  of  carbon  ;  remove  the 
sulphur  by  washing  with  alcohol  alone,  and  after- 
wards wash  well  with  water. 

7 


74:  PHOTOGRAPHY. 

If  you  fix  it  with  a  warm  bath  of  hyposulphite, 
your  proof  disappears,  for  the  heat  decomposes  the 
hyposulphite.  Liquid  ammonia  fixes  very  well ;  it 
gives  red  colors  :  the  image  fixed  in  this  way  is 
very  solid  if  you  wash  it  well  afterwards. 

71.  With  the  following  process,  you  obtain  the 
pure  black  and  white,  the  pure  black,  and  the 
bluish-green.  You  prepare  your  positive  paper  in 
the  ordinary  way,  with  the  chloride  of  sodium  and 
nitrate  of  silver.  You  expose  it  to  the  light  a 
longer  time  than  when  you  prepare  it  by  the  ordi- 
nary process.  It  must  have,  when  the  proof  comes 
out  of  the  frame — 1st,  a  violet  color  perfectly  clear, 
and  in  the  dark  parts  bluish-black  in  the  shades. 
2d.  A  violet  color,  and  very  black  in  the  shades. 
3d.  A  sepia  color  in  the  light  part  of  a  picture, 
that  is  greenish-black  or  bluish-green  in  the  shades. 

After  exposition,  wash  well  the  proof,  and  put  it 
in  the  following  bath : 

Distilled  water    -      -      -      -  2  lbs. 

Chloride  of  gold  15  grains. 

Hydrochloric  acid  1  ounce. 

"When  the  shades  are  very  distinct,  and  all  the 
details  of  the  negative  are  visible,  wash  well,  and 
then  put  it  in  the  following  bath  : 


POSITIVE  PAPER.  75 

Hyposulphite  of  soda     -      -  1  part. 

Water  6  " 

Leave  it  in  30  minutes,  and  then  wash  it. 

72.  In  using  the  hyposulphite  containing  chlo- 
ride of  silver,  you  will  have  some  very  beautiful 
colors,  but  it  is  good  to  pass  afterwards  in  the  new 
hyposulphite.  By  the  addition  of  hydrochloric  acid, 
you  transform  all  nitrate  of  silver  into  chloride ; 
and  it  precipitates  gold  and  silver,  and  by  this 
way  the  hyposulphite  makes  no  precipitation  on 
the  white ;  the  chloride  of  silver  being  pure,  is 
dissolved  easily  by  hyposulphite,  which  is  without 
action  on  the  gold.  This  process  is  not  cheap,  but 
it  gives  such  good  results,  we  prefer  it  to  any 
other. 

ISTo  care  or  expense  ought  to  be  spared :  in  order 
to  have  good  pictures,  we  recommend  this  process 
to  all. 


PART  V. 
PREPARATION 

OF 

CHEMICAL  PRODUCTS. 


PREPARATION  OF  CHEMICAL  PRODUCTS. 


73.  We  give  below  a  list  of  chemical  products, 
which  are  mostly  used  in  Photography. 


Acetic  acid  (glacial). 
Sulphuric  acid. 
Gallic  acid. 


Ammonia. 


Acids. 

Nitric  acid. 
Pyrogallic  acid. 
Hydrochloric  acid. 

Bases. 

Caustic  potash. 


Haloid  Salts. 
Iodide  of  potassium.  Fluoride  of  potassium. 

"     "  ammonia. 

"     "  silver. 
Cyanide  of  potassium. 
Bromide  "  11 


"      "  ammonium. 
Chloride  of  sodium. 
"      "  strontium. 
"       "  silver. 


ammonium. 


M      "  silver. 


"  mercury. 
"  gold. 


Chloride  of  ammonium. 


80 


PHOTOGE  APHY . 


Salts. 

Nitrate  of  silver.  Hyposulphite  of  soda. 

"     "  zinc.  Hypochlorate  of  potash. 

"     "  potash.  Acetate  of  ammonia. 

Protosulphate  of  iron.  "     "  lime. 

Persulphate  of  iron.  "     "  lead. 

Citrate  of  iron  and  ammonia. 

Neutral  Substances. 
Alcohol.  Amylaceous  matters. 

Gun-cotton.  Sulphuric  ether. 

Starch.  Animal  black. 


I. — Acetic  Acid. 
Formula,  OJ  H4  0^  H  0  =  120. 

74.  It  is  preferable  to  buy  it  rather  than  to  pre- 
pare it.  You  ought  to  be  sure  that  it  is  pure  ;  to 
ascertain  which,  evaporate  a  certain  quantity ;  if 
it  is  pure,  no  residuum  is  left. 

Although  it  may  not  leave  any  residuum,  still  it 
may  contain  a  great  quantity  of  sulphuric  acid. 
You  can  assure  yourself  of  this  by  saturating  a 
little  acetic  acid  with  potash,  and  pouring  upon  it 
some  nitrate  of  baryta,  or  some  chloride  of  barium. 
If  it  forms  a  white  precipitate,  insoluble  in  nitric 
acid,  it  is  a  proof  that  it  contains  sulphuric  acid, 


PREPARATION  OF  CHEMICAL  PRODUCTS.  81 

and  then  it  is  not  good.  It  is  employed  in  Pho- 
tography, added  to  a  solution  of  nitrate  of  silver,  to 
facilitate  the  decomposition  of  nitrate  of  silver,  and 
to  assist  the  penetrations  of  the  solutions  into  the 
paper.  It  is  also  employed  to  remove  the  spots  on 
the  negative  proofs,  formed  by  the  oxide  of  silver. 

II. — Sulphuric  Acid. 
Formula,  SO3 HO  =49. 

75.  This  acid  is  employed  only  to  prepare  gun- 
cotton  ;  that  found  in  commerce  is  good  enough  for 
this  purpose. 

III. — Hydrochloric  Acid. 
Formula,  H  CI  =  36-5. 

76.  This  acid  is  found  pure  in  commerce.  It  is 
employed  in  Photography,  diluted  with  water,  to 
give  a  rich  brown  tone  to  the  proof,  after  it  has 
been  in  the  bath  of  hyposulphite  of  soda.  With 
nitric  acid  it  forms  aqua  regia,  used  to  dissolve 
gold. 

IY. — Nitric  Acid. 
Formula,  NO5 H  0  =  65. 

77.  This  acid  can  also  be  obtained  pure  in  com- 


82 


PHOTOGRAPHY. 


merce,  and  we  indicate  the  way  to  know  if  it  is  so. 
It  is  used  in  Photography  to  form  the  nitrate  of 
silver,  and,  mixed  with  muriatic  acid,  it  forms 
aqua  regia.  It  turns  the  sulphate  of  protoxide  of 
iron  into  peroxide.  Impure,  it  is  used  to  clean 
dishes. 

To  ascertain  if  nitric  acid  is  pure,  take  a  quan- 
tity of  acid  to  test.  Divide  it  into  two  parts.  In 
one  you  pour  chloride  of  barium :  there  should  be 
no  precipitate  ;  if  you  have  one,  it  is  an  indication 
of  sulphuric  acid  in  it.  In  the  other,  pour  some 
drops  of  nitrate  of  silver  :  if  you  have  a  precipi- 
tate, it  contains  chlorine  ;  if  the  nitric  contains 
chlorine  or  sulphuric  acid,  it  should  be  rejected 
as  impure. 

V. — Gallic  Acid. 

Formula,  C7  H5  08  =  95. 

78.  This  acid  is  used  to  develop  negatives  on 
paper :  with  the  salts  of  silver  it  gives  a  ■  black 
color ;  the  salts  of  silver  lose  their  oxygen  by  the 
action  of  light.  This  acid  precipitates  all  salts'  of 
silver  which  are  in  a  state  of  suboxide.  It  is  not 
useful  to  use  it  concentrated  ;  15  to  30  grains  for  a 
quart  of  distilled  water  are  sufficient.    When  you 


PREPARATION  OF  CHEMICAL  PRODUCTS.  83 

develop,  it  is  good  to  add  a  little  aceto-nitrate  of 
silver,  as  it  gives  more  intensity  to  the  proof. 

VI. — Pyrogallic  Acid. 

Formula,  C6H3  O8  =  63. 

79.  When  you  have  not  every  thing  convenient 
•  for  making,  it  is  much  more  preferable  to  purchase 
this  article  than  to  prepare  it.  But  you  must  be 
sure  that  it  does  not  contain  a  particle  of  gallic 
acid.  To  ascertain  this,  dissolve  a  small  quantity 
in  water,  and  pour  in  it  a  solution  of  sulphate  of 
iron  ;  the  liquor  takes  a  very  fine  reddish-brown 
color  if  it  contains  any  gallic  acid.  If  it  is  impure, 
the  color  becomes  blue. 

VII. — Ammonia. 

Formula,  A3H3  =  17. 

80!  Ammonia  is  a  gas  very  soluble  in  water; 
this  liquid  dissolves  about  780  times  its  volume  of 
ammonia.  It  is  possible  to  obtain  it  very  pure  in 
commerce.  Ammonia  dissolves  the  chloride  of 
silver  :  if  you  add  it  drop  by  drop  to  the  nitrate  of 
silver,  you  will  obtain  a  precipitate,  soluble  in  an 


84:  PHOTOGRAPHY. 

excess  of  ammonia.  This  liquid  is  used  to  prepare 
the  positive  paper.  Employ — 

Distilled  water  1  ounce. 

Mtrate  of  silver  -      -      -      -      -    35  grains. 

This  compound  is  very  dangerous  to  use,  as  it  pro- 
duces the  mixture  known  as  explosive  silver. 

One  property  of  the  ammonia  is,  that  it  keeps 
the  collodion  a  long  time,  and  prevents  its  decom- 
position ;  a  few  drops  of  ammonia  in  some  pounds 
of  collodion  are  sufficient.  This  property  was  in- 
dicated by  M.  Dussauce. 

Ammonia  added  to  the  bath  of  hyposulphite,  to 
fix  the  positive  proofs,  gives  to  them  a  reddish- 
brown  tint. 

VIII. — Caustic  Potash. 
Formula,  K  O,  H  0  —  56. 

81.  It  precipitates  the  oxide  of  silver  ;  it  is  used 
also  in  weak  solutions,  to  give  a  variety  of  tints  to 
a  proof,  when  it  has  been  fixed  by  the  hyposul- 
phite of  soda. 

IX. — Iodide  of  Potassium. 
Formula,  IK  =  166. 

82.  This  substance  is  very  useful  in  Photog- 


PREPARATION  OF  CHEMICAL  PRODUCTS.  85 

raphy  ;  it  is  used  to  render  sensitive  the  collodion, 
paper,  &c,  &c.  It  is  also  used  to  make  iodide  of 
silver,  which  is  insoluble  in  water,  and  soluble  in 
the  hyposulphite  of  soda.  It  is  very  pure  in  com- 
merce. 

X. — Iodide  of  Ammonium. 
Formula,  HIAzHs  =  145. 

83.  This  salt  is  used  for  the  same  purposes  as 
the  iodide  of  potassium,  but  it  is  more  sensitive ; 
and  a  proof  prepared  with  this  salt  is  developed 
easily  with  gallic  acid  for  paper,  or  pyrogallic  acid 
for  collodion.  It  can  be  purchased  very  pure,  but 
in  some  instances  it  is  apt  to  contain  carbonate  of 
ammonia. 

XI. — Iodide  of  Silver. 
Formula,  I  Ag  =  235. 

84.  Iodide  of  silver  is  obtained  by  the  decompo- 
sition of  nitrate  of  silver  by  iodide  of  potassium. 
You  have  the  following  reaction  : 

IK  +  N05AgO  =  IAg  +  N05KO. 

You  must  add  the  iodide  of  potassium  to  the 
nitrate  of  silver ;  wash  the  preciDitate  with  water, 
8 


86  PHOTOGRAPHY. 

and  dry  it.  The  iodide  of  silver  is  soluble  in 
iodide  of  potassium.  This  iodide  is  used  some- 
times to  sensibilize  collodion,  and  to  put  in  the 
positive  bath  for  fixing  positives. 

XII.  — Fluoride  of  Potassium. 

Formula,  F1K  =  103. 

85.  This  body,  in  small  proportions,  gives  a 
great  sensitiveness  to  the  bath;  and  principally, 
when  it  is  mixed  with  iodide  of  potassium  or  am- 
monium :  in  the  proportion  of  jq  of  iodide  of 
ammonium  in  the  collodion,  it  renders  it  very  sen- 
sitive. 

XIII.  — Fluoride  of  Ammonium. 
Formula,  FlHAzH3  =  37. 

86.  Its  properties  are  the  same  as  fluoride  of 
potassium,  only  that  it  decomposes  very  rapidly. 

X1Y. — Cyanide  of  Potassium. 
Formula,  K  Oy  =  65. 

87.  This  salt,  by  its  decomposition  with  the 
nitrate  of  silver,  gives  a  combination  of  cyanide  of 


PREPARATION  OF  CHEMICAL  PEODUCTS.  87 

silver  which  is  very  sensitive,  and  it  is  added  to 
iodide  and  fluoride  of  potassium  to  have  an  ex- 
treme sensitiveness.  This  substance  dissolves  all 
insoluble  salts  of  silver.  It  can  be  used  to  clean  a 
proof  which  is  covered  with  black  spots.  It  is 
used  also  to  clean  the  hands;  but  it  it  must  be 
used  with  great  precaution,  for  it  is  a  violent 
poison. 

XY. — Chloride  of  Sodium. 
Formula,  CI  Na  =  58-5. 

88.  This  substance  is  the  common  salt;  it  is 
used  to  prepare  the  positive  paper,  and  forms  chlo- 
ride of  silver  with  nitrate.  It  is  used  also  to  obtain 
the  chloride  of  silver,  in  mixing  with  a  solution  of 
nitrate  of  silver. 

XYI. — Chloride  of  Strontium. 
Formula,  CI  Sr  =  134. 

89.  This  compound  is  not  very  useful.  .You  can 
use  it  if  you  have  no  other  chloride.  It  is  very 
soluble  in  water. 


88  PHOTOGRAPHY. 

XYII. — Chloride  of  Silver. 
Formula,  CI  Ag  =  143-5. 

90.  We  have  said,  that  in  the  preparation  of 
positive  paper,  you  employ  275  grains  of  chloride 
of  silver.  It  is  necessary  to  prepare  this  yourself ; 
and  for  this  purpose  you  take  450  grains  of  nitrate 
of  silver,  which  you  dissolve  in  filtered  water. 
Pour  in  it  an  excess  of  solution  of  chloride  of 
sodium ;  you  will  then  have  a  white  precipitate. 
It  is  necessary  to  pour  in  chloride  of  sodium  as 
long  as  you  have  a  white  precipitate.  Allow  it  to 
repose  ;  decant  the  clear  water.  This  substance  is 
acted  upon  by  light  very  rapidly.  It  is  used  to 
prepare  positive  paper,  and  the  bath  to  fix  the  pos- 
itive proofs.  It  is  insoluble  in  water  :  acids,  alka- 
lines,  cyanides,  and  hyposulphites  dissolve  it.  It 
darkens  rapidly  under  the  influence  of  light :  it  is 
the  most  sensitive  of  all  salts  of  silver. 

XVIII. — Bichloride  of  Mercury. 
Formula,  Cl2Hg  =  l70. 

91.  This  salt  is  used  only  to  convert  the  nega- 
tives on  collodion  into  positives  ;  for  this  purpose 


PREPARATION  OF  CHEMICAL  PRODUCTS.  89 


make  a  saturated  solution  of  this  salt  in  hydro- 
chloric acid ;  to  one  part  of  this  solution  add  six 
parts  of  distilled  water.  This  salt  is  very  good  to 
obtain  good  negatives.  After  developing,  wash  it 
well,  and  pass  it  through  the  bath  of  bichloride  of 
mercury ;  wash  and  fix  it  afterwards  ;  the  proof  is 
blacker  :  by  this  bath  it  becomes  positive,  but  the 
hyposulphite  renews  it  to  negative.  We  recom- 
mend this  salt. 

XIX. — Chloride  of  Gold. 
Formula,  Air5  CP  =  502. 

92.  To  prepare  this  salt,  dissolve  one  part  of 
gold  in  four  parts  of  aqua  regia  (one  part  nitric 
acid,  four  parts  hydrochloric  acid) ;  evaporate  it, 
dry  it,  and  dissolve  in  water.  This  salt  is  used  to 
obtain  very  fine  colors,  after  having  fixed  positive 
proofs  by  hyposulphite  ;  gold  is  precipitated  black 
on  silver,  and  gives  very  fine  effects. 

XX. — Hydrochlorate  of  Ammonia. 
Formula,  H  CI  Az  Hs  =  54. 

93.  This  salt  is  sold  very  pure  in  commerce. 
It  is  soluble  in  alcohol,  and  can  be  used  very  well 

8* 


90 


PHOTOGRAPHY. 


for  positive  paper,  with  albumen  ;  when  the  paper 
is  dry,  pass  it  through  a  bath  of  commercial  alcohol, 
containing  five  per  cent,  of  hyclrochlorate  of  am- 
monia. Its  employment  is  preferable  to  chloride 
of  sodium  for  positive  paper,  for  it  does  not  ab- 
sorb water  as  this  salt  does. 

XXI. — Bromide  of  Potassium. 
Formula,  Br  K  =  119. 

94.  This  salt  is  used  to  form  the  bromide  of  sil- 
ver, insoluble  in  reagents.  It  is  also  less  sensitive 
than  the  iodide.  If  you  mix  it  with  chloride  of 
sodium,  for  positive  proofs,  you  obtain  them  of  a 
grayish-black  color  ;  for  which  use — 

Distilled  water     -      -      -  10  parts. 

Bromide  of  potassium  -  -  -  1  " 
Cliloride  of  sodium       -      -       -       1  u 

It  is  used  also  to  fix  negative  proofs  ;  but  for  this 
purpose  the  hyposulphite  is  much  better. 

XXII.' — 'Bromide  of  Ammonium. 
Formula,  Br  Az  H3  =  97. 

95.  The  use  of  this  salt  is  about  the  same  as  the 


PEEPAEATION  OF  CHEMICAL  PEODtPCTS.  91 

bromide  of  potassium.  Dissolved  in  water,  it 
forms  an  excellent  bath  to  fix  positives. 

Distilled  water     -      -      -  100  parts. 

Bromide  of  ammonium  -  100  " 

Leave  your  proof  lialf  an  hour,  and  wash  it  well 
afterwards. 

It  can  be  used  also  for  negative  and  positive 
paper.    The  best  formula  is  as  follows  : 

Water   1000  parts. 

Iodide  of  potassium  -  -  -  15  " 
Bromide  of  ammoium  -  -  4  " 
Sugar  of  milk    -      -      -      -        40  " 

XXIII.  — Beomide  of  Silvee. 
Formula,  BrAg  =  188. 

96.  You  obtain  it  by  the  decomposition  of  nitrate 
of  silver  by  cyanide  of  potassium ;  it  is  a  very  sen- 
sitive salt,  but  less  so  than  the  iodide. 

XXIV.  — Niteate  of  Silvee. 
Formula,  N"  O5  Ag  O  =  24T0. 

97.  In  a  porcelain  dish  put  a  piece  of  silver  coin ; 
pour  upon  it  an  excess  of  pure  nitric  acid.  The 


92 


PHOTOGRAPHY. 


reaction  is  almost  immediate,  and  violent ;  when 
it  is  nearly  dissolved,  warm  the  liquid  ;  when  all 
is  dissolved,  evaporate  to  dryness ;  fuse  or  melt,  so 
that  the  nitrate  of  copper  will  be  decomposed ; 
redissolve  it,  and  filter.  The  solution  of  nitrate  of 
silver  is  evaporated  to  dryness  ;  fuse  and  flow,  that 
is,  pour  it  on  a  clean  surface  of  porcelain :  then 
the  salt  is  very  pure.  It  is  used  to  obtain  all  in- 
soluble salts  of  silver,  iodide,  chloride,  &c,  &c. 
It  is  much  better  to  use  it  fused,  as,  when  crystal- 
lized, it  always  contains  a  little  acid  ;  it  is  impos- 
sible to  obtain  it  crystallized  without  its  having 
acid  in  it. 


XXY. — Nitrate  op  Zinc. 
Formula,  ZnON06  =  94. 

98.  You  obtain  this  by  dissolving  zinc  in  nitric 
acid,  and  evaporating  the  solution. 

Added  to  the  bath  of  aceto-nitrate  of  silver,  it 
augments  sensitiveness;  and  by  the  precipitation 
of  the  oxide,  it  forms  a  size  for  paper.  To  prepare 
it  as  a  size  for  paper,  make  the  following  bath : 

Distilled  water    -      -      -  100  parts. 

Nitrate  of  zinc    -  6  " 


PREPARATION  OF  CHEMICAL  PRODUCTS.  93 

Pass  your  paper  through  it ;  dry  it,  and  operate 
as  we  have  before  indicated. 

XXYI. — Nitrate  of  Potash. 
Formula,  NO5 K 0  =  101. 

99.  It  is  used  only  to  prepare  gun-cotton.  As  it 
is  found  in  commerce,  it  is  very  pure.  For  this 
purpose  it  ought  to  be  well  pulverized. 

XXVII. — Hyposulphite  of  Soda. 
Formula,  S2  O2  Ka  O  =  124. 

100.  It  is  found  pure  in  commerce.  It  is  very 
much  used  in  Photography,  to  dissolve  insoluble 
salts  of  silver.  But  when  you  use  it,  care  must  be 
taken  that  the  liquids  are  not  acid,  for  they  de- 
compose the  hyposulphite,  so  that  the  sulphur  is 
freed,  and  gives  to  the  proof  a  gray  dirty  color.  It 
is  used  to  fix  both  negatives  and  positives. 

XXVHI. — Sulphate  of  Protoxide  of  Iron. 
Formula,  S  O3  Fe  O  =  76. 

101.  To  be  sure  to  have  this  body  to  the  mini- 
mum of  oxidation,  it  is  much  better  to  prepare  it 


94 


PHOTOGEAPHY. 


yourself ;  for  this  purpose,  in  a  small  matrass  of 
glass,  introduce  some  water,  iron  (in  powder),  and 
sulphuric  acid.  Reaction  takes  place  without  heat ; 
when  the  reaction  subsides  somewhat,  you  must 
warm  it.  It  is  necessary  to  have  an  excess  of  iron. 
The  following  is  the  result  of  the  chemical  reac- 
tion : 

S  O3  +  Fe  +  H  0  =  S  03Fe  0  +  H. 

The  water  is  decomposed  ;  the  oxygen  unites  with 
the  iron  to  form  protoxide  of  iron,  which  com- 
bines with  the  sulphuric  acid  to  form  sulphate  of 
protoxide  of  iron,  the„  hydrogen  being  disengaged. 
Filter  the  solution ;  evaporate  it  from  the  contact 
of  air,  and  it  will  crystallize.  It  is  necessary  to 
prepare  only  a  small  quantity  at  a  time,  as  it  is 
transformed  by  the  air  into  persulphate. 

XXIX. — Persulphate  of  Ikon. 

Formula,  3  (S  O3)  Fe5  O3  =  200. 

102.  To  obtain  this  salt,  treat  the  sulphate  of 
protoxide  of  iron  by  nitric  acid ;  evaporate  and  dry 
it,  until  you  have  no  nitric  acid.  This  salt  is  used 
to  fix  negatives  on  glass. 


PEEPAEATION  OF  CHEMICAL  PEODTTCTS.  95 

XXX. — Hypochloeate  of  Potash. 
Formula,  CI  0  K  O  =  88*5. 

103.  You  can  get  this  article  pure  in  commerce. 
It  is  used  to  clean  paper.  For  this  purpose,  acid 
to  it  the  half  of  its  volume  of  water.  It  also  fixes 
positive  proofs. 

XXXI. — Acetate  of  Ammonia. 
Formula,  C4  H4  O4  Az  Hs  =  80. 

104.  It  accelerates  the  developing  of  negative 
proofs  on  gallic  acid,  and  continues  the  reduction 
which  is  begun  by  the  light ;  but  it  is  dangerous 
to  use  it,  for  sometimes  its  action  is  so  rapid,  that  it 
destroys  all  the  proofs. 

XXXII. — Acetate  of  Lime. 
Formula,  C4  H4  O4  Ca  0  =  129. 

105.  United  with  gallic  acid,  it  is  used  to  de- 
velop very  quickly.  It  decomposes  iodide  of  sil- 
ver, and  forms  acetate  of  silver  and  iodide  of 
lime,  after  the  oxide  of  silver  is  reduced  and  pre- 


96  PHOTOGRAPHY. 

cipitated  black.  This  salt  also  lias  a  too  rapid 
action. 

XXXIII. — Acetate  of  Lead. 

Formula,  C4  H6  O6  Pb  0  =  181-6. 

106.  Its  use  is  the  same  as  acetate  of  ammonia 
and  lime,  bnt  it  is  not  so  dirty ;  added  to  hypo- 
sulphite, it  is  used  to  fix  positive  proofs.  From 
5  to  25  parts  of  this  salt  for  100  parts  of  hyposul- 
phite, you  obtain  red,  violet,  or  black  colors. 


XXXIV. — Ammoniaco-Citrate  of  Iron. 

107.  Take  citrate  of  ammonia ;  put  into  it  some 
iron  powder  ;  leave  to  evaporate,  filter,  and  then 
evaporate  to  dry.  This  solution  is  sensitive.  We 
have  seen  it  used  with  paper. 

XXXV.— Ether. 

108.  The  ether  employed  ought  to  be  anhy- 
drous ;  that  is  to  say,  it  ought  to  have  been  rec- 
tified with  lime.  Put  into  the  ether  a  piece 
of  blue  litmus  paper,  so  as  to  be  sure  it  is  not 


PREPARATION  OF  CHEMICAL  PRODUCTS.  97 

acid.  If  the  paper  becomes  red,  it  must  not  be 
used,  for  the  collodion  will  be  destroyed  in  a 
short  time. 

XXXYL— Alcohol. 

109.  The  alcohol  found  in  commerce  of  95  per 
cent,  is  good  enough,  if  it  contains  no  acid, 

XXXVII. — Gtjn-cotton. 

110.  Take  300  grains  of  dried  nitrate  of  potash, 
in  fine  powder ;  introduce  it  into  a  mortar,  and 
pour  on  600  grains  of  sulphuric  acid.  Mix  it  well ; 
and  gradually  immerse  7 5  grains  of  pure  cotton  ; 
leave  the  cotton  in  a  quarter  of  an  hour  ;  remove 
to  a  funnel,  and  wash  it  well  with  lukewarm  water. 
When  the  cotton  is  free  from  acid,  wash  it  well 
three  or  four  different  times  with  distilled  water. 
Dry  it  in  a  proper  temperature,  covered  with  fil- 
tering paper,  to  keep  off  the  dust.  If  during 
the  process  reel  vapors  are  evolved,  the  cotton 
is  good  for  nothing,  and  a  new  portion  must  be 
prepared. 

9 


98 


PHOTOGRAPHY. 


XXXVIIL— Pure  Cotton. 

111.  Take  wadding,  and  treat  it — 1st,  with  a 
solution  of  weak  potash.  2d.  With  water. v  3d. 
With  hydrochloric  acid.  4th.  With  boiling  dis- 
tilled water,  and  drv  it. 

XXXIX. — Animal  Black. 

112.  It  is  found  very  pure  in  commerce.  It  is 
used  to  purify  the  old  bath  of  aceto-nitrate  of  sil- 
ver, and  it  gives  more  sensitiveness  to  the  bath, 
because  it  forms  phosphate  of  silver,  which  is  solu- 
ble in  acetic  acid.  There  is  a  great  difference  be- 
tween the  baths ;  one  with  animal  black,  and  the 
other  without;  the  one  with  the  animal  black 
being  very  sensitive,  while  the  other  is  not. 

XL. — Starch  and  other  Amylaceous  and  Fatty 
Matters  used  for  Negative  Paper. 

113.  Starch  is  soluble  in  boiling  water,  and  be- 
comes insoluble  in  cold  water,  when  it  is  dried. 
The  best  way  to  obtain  this  starch,  is  to  use  rice- 


PREPARATION  OF  CHEMICAL  PRODUCTS.  99 

water.  Starch  forms  with  iodine  a  compound 
which  has  a  bluish  color. 

A  warm  solution  of  gelatine  applied  on  paper 
with  iodine,  gives  a  size  to  paper,  which  is  insolu- 
ble in  cold  water. 

Albumen  is  also  very  good  to  use  for  this  prop- 
erty, as  it  becomes  insoluble  in  water  when  it  is 
warm. 

Inuline  is  also  very  good,  because  it  is  in- 
soluble in  cold  water,  although  it  is  very  soluble 
in  hot. 

Eesins,  camphor,  &c,  &c,  are  also  very  good 
in  solution  of  alcohol,  and  by  insolubility  in  water. 
It  is  the  same  for  collodion. 

In  general,  to  have  a  good  size,  you  must  em- 
ploy a  substance  soluble  in  the  liquid  used  to  dis- 
solve the  other  preparations,  and  after  which  it 
becomes  insoluble  in  the  other  preparation. 

The  sugar  of  milk  is  very  good  :  to  prepare  it, 
concentrate  the  whey ;  when  the  liquid  becomes 
cold,  it  deposits  crystals,  which  are  the  sugar  of 
milk. 

Dextrine  is  the  starch  treated  by  a  solution  of 
sulphuric  acid  and  water  :  its  only  use  is  to  trans- 
fer a  proof  on  paper. 


100 


PHOTOGRAPHY. 


114.  Such  are  the  chemical  products  used  in 
Photography.  "We  hope  that  everybody  will  fiud 
in  this  part  of  the  work  all  the  information  neces- 
sary for  the  use  and  tests  of  the  chemicals  and 
their  reactions. 


PART  VI. 

THE  APPARATUS,  FOCUS, 

AND 

THEORY  OF  THE  PHOTOGRAPHIC  PHENOMENA. 


THE  APPARATUS. 


115.  The  simple  camera  obscura,  invented  by 
Porta,  in  the  year  1650,  served  for  photographic 
experiments  as  long  as  the  art  remained  in  its  in- 
fancy ;  but  as  the  art  progressed,  it  was  soon  found 
that  this  instrument  was  too  imperfect  to  satisfy 
the  increasing  demands  made  upon  it.  A  great 
many  improvements  were  made  in  the  camera  by 
the  combined  exertions  of  Petzval  and  Voightlan- 
der.  But  even  this  improved  camera  is  by  no 
means  every  thing  that  could  be  desired.  The  de- 
mands that  may  be  justly  made  upon  an  apparatus, 
truly  deserving  the  name  of  perfect,  are  as  follows  : 
It  must  give  a  large-sized  picture,  correctly  drawn, 
and  equally  distinct  in  all  parts  :  it  must  command 
a  most  intense  light,  and  it  must  be  adapted 
equally  for  portraying,  and  for  taking  views  of 
architectural  objects.  Now,  up  to  the  present  time, 
the  problem  of  fulfilling  all  these  conditions 


104 


PHOTOGRAPHY. 


equally,  has  not  been  solved  ;  indeed,  one  excludes 
the  other.  If  the  picture  is  to  be  large,  of  equal 
clearness  and  distinctness  in  all  parts,  even  to  the 
border,  and  equally  so  for  near  objects  as  for  those 
farther  off,  the  focal  distance  must  be  proportion- 
ately longer,  and  the  aperture  through  which  the 
luminous  rays  enter  must  be  smaller.  The  neces- 
sary consequence  of  this  mode  of  construction  is, 
that  the  apparatus  does  not  command  a  sufficiently 
intense  light  to  answer  the  purpose  of  taking  por- 
traits with  it.  On  the  other  hand,  if  the  focal 
distance  is  lessened,  and  the  aperture  enlarged 
(with  the  best  suited  to  the  purpose),  the  apparatus 
will  then  command  a  greater  amount  of  light,  and 
will  accordingly  be  better  adapted  for  the  taking 
of  portraits.  But  it  will  be  found  that  this  has 
been  achieved  only  at  the  expense  of  the  size  of 
the  picture,  and  of  the  desired  correct  delineation, 
and  equal  clearness  and  distinctness  in  all  parts. 

116.  An  apparatus  so  constructed,  is  therefore 
but  imperfectly  adapted  for  taking  views  of  land- 
scapes or  of  architectural  objects ;  and  although 
small  views  may,  if  need  be,  be  taken  with  it,  by 
placing  screens  before  it  to  reduce  the  aperture, 
the  productions  so  obtained  are  very  inferior  to  the 
views  taken  with  an  apparatus  of  greater  focal  dis- 


THE  APPARATUS. 


105 


tance  and  smaller  aperture.  This  applies  more 
especially  to  pictures  taken  on  paper  ;  since  from 
the  unequal  texture  of  that  material,  the  minute 
details  of  the  object  delineated  will  necessarily 
grow  indistinct  and  confined,  or  even  vanish  alto- 
gether if  the  surface  acted  upon  is  too  restricted 
to  reflect  these  details  on  a  sufficiently  large  scale. 

The  duty  of  the  optician  consequently  is,  to  con- 
struct and  combine  the  apparatus  in  such  a  man- 
ner as  to  produce  the  best  total  effect  in  every 
individual  case,  which  of  course  requires,  in  the 
first  place,  due  attention  to  the  choice  of  curva- 
tures in  the  lenses,  as  on  this  principally  depends 
the  accuracy  of  the  impression.  A  proper  achro- 
matization  of  the  glasses  will  obviate  the  occur- 
rence of  colored  edges  in  the  images  taken.  The 
glass  for  the  lens  ought  to  be  as  white  as  possible, 
and  pure  and  even  throughout,  —  requirements 
which  it  is  not  always  easy  to  fulfil.  Perfect  white- 
ness is  not,  however,  absolutely  necessary  ;  on  the 
contrary,  a  violet  tint  of  the  glass  is  rather  desira- 
ble than  otherwise,  provided  the  coloration  be  not 
too  intense,  since  this  would  tend  to  lessen  the 
luminousness  of  the  apparatus,  more  particularly 
with  larger  lenses,  on  account  of  the  greater  thick- 
ness of  the  glass.    There  are  not  unfrequently  little 


106 


PHOTOGRAPHY. 


bubbles  and  small  black  spots  in  the  vitreous  mass ; 
however,  if  there  are  not  too  many  of  them,  nor 
over-large  ones,  their  presence  matters  little,  as 
may  be  readily  proved  by  a  simple  experiment : 
Cut  a  small  round  piece  of  paper,  and  paste  it  with 
gum  on  the  object-glass  in  the  centre :  a  picture 
taken  with  this  glass  will  show  no  difference  from 
another  taken  with  a  clear  glass  ;  at  the  most,  the 
time  of  exposure  may  require  to  be  prolonged  a 
little ;  that  is,  if  the  piece  of  paper  pasted  on  the 
object-glass  is  of  rather  large  size  in  proportion  to 
the  aperture.  But  the  glass  must  be  free  from 
tears ;  and,  indeed,  no  conscientious  optician  will 
knowingly  make  use  of  glass  having  tears,  which 
requires  a  practised  eye  to  detect.  Still,  even  with 
glasses  of  this  kind,  an  apparatus,  otherwise  prop- 
erly constructed,  is  preferable  to  one  with  faultless 
glasses,  but  with  a  defective  combination  of  the 
lenses  ;  the  defect  caused  by  tears  being,  after  all, 
imperceptible  in  the  miniature  picture  of  the 
camera,  or,  at  all  events,  scarcely  visible  to  the 
naked  eye. 

To  be  able  to  pronounce  a  correct  opinion  on  the 
quality  of  a  photographic  aj)paratus,  the  one  thing 
needful  is  to  take  a  picture  with  it,  in  two  appara- 
tuses of  the  same  construction :  that  one  is  the 


THE  APPARATUS. 


107 


best  which  produces  the  larger  picture  of  the  two, 
of  equal  or  superior  distinctness,  and  in  the  short- 
est time. 

Besides  the  quality  of  the  object-glass,  and  the 
proper  fixing  of  the  chemical  focus  (of  which  we 
shall  treat  in  the  next  section),  the  accurate  adjust- 
ment of  the  apparatus  also  forms  an  essential  con- 
dition for  the  good  success  of  photographic  opera- 
tions. The  prepared  side  of  the  plate  or  paper,  on 
which  the  image  is  to  be  produced,  must  be  placed 
exactly  in  the  spot  previously  occupied  by  the 
roughened  side  of  the  ground-glass  plate  or  focus- 
ing glass  (the  side  turned  towards  the  object-glass) ; 
if  it  is  not  made  to  occupy  that  exact  position,  the 
clearness  of  the  impression  produced  will  suffer  in 
proportion  to  the  extent  of  the  deviation  from  it. 

117.  The  construction  that  has  been  given  to  the 
camera  obscura,  and  to  the  frame  for  the  reception 
of  the  plate  or  paper,  varies  greatly ;  however,  all 
the  modifications  introduced  have  essentially  one 
and  the  same  object  in  view,  namely,  the  facilita- 
ting of  certain  manipulations.  I 

In  Yoigtlander's  apparatus,  the  camera  consists 
of  a  large  cylindrical  brass  tube  ;  in  others  it  is  a 
square  wooden  box  ;  the  latter  again  varies  greatly 
in  size,  and  in  the  arrangement  of  the  details  of 


108 


PHOTOGRAPHY. 


construction.  But  they  all  agree  in  this  point,  in 
having  the  object-glass  set  in  the  anterior  part ; 
the  roughened  or  unpolished  glass-plate  or  focus- 
ing glass  (for  which  is  substituted  the  frame  car- 
rying the  plate  or  paper)  being  placed  in  the 
posterior  part.  One  of  the  great  advantages  of 
this  apparatus  of  Voigtlander's  is,  that  when  taken 
to  pieces  and  packed  in  a  box,  it  occupies  only  a 
small  space,  and  may  consequently  be  readily  car- 
ried about,  which  makes  it  very  convenient  for 
travelling  purposes.  Moreover  the  material  of  the 
apparatus  being  brass  or  metal,  there  is  no  fear  of 
absorption  of  iodine  or  bromine,  or  of  aqueous  va- 
pors. On  the  other  hand,  this  apparatus  has  also 
its  drawbacks :  the  plates  at  present  in  use  being 
square,  the  edges  must  necessarily  be  cut  off,  to  fix 
them  for  the  round  frame  ;  moreover,  the  apparatus 
requires  repeated  moving  in  the  course  of  every 
operation,  and  the  naturally  low  temperature  of  the 
metal  demands  a  longer  exposure  of  the  plate. 

The  construction  of  the  camera  which  is  even  at 
present  most  generally  used,  differs  from  the  pre- 
ceding principally  in  this,  that  the  large  brass  cyl- 
inder is  replaced  by  a  square  wooden  box. 

This  power  of  lengthening  or  expanding  the 
camera,  is  an  advantage  which  Yoigtlander's  ap- 


THE  APPARATUS. 


109 


paratus  does  not  possess.  If  it  is  intended  to  take 
very  small  pictures  with  the  latter  apparatus,  the 
camera  must  be  removed  to  a  great  distance  from 
the  object  to  be  portrayed ;  and  this  is  in  many 
cases  difficult,  and  in  others  altogether  impracti- 
cable. 

118.  There  exists  a  camera  of  a  different  con- 
struction, which  combines  all  the  advantages  of 
this  camera  :  it  consists  in  the  stretching  a  bag  of 
cloth  or  caoutchouc,  and  in  the  simple  way  in 
which  the  paper  or  plate  may  be  adjusted  to  any 
angle  which  may  be  thought  adapted  to  obtain  a 
good  focus.  Another  advantage  is  the  vertical 
mobility  of  the  object-glass,  whereby  the  object  to 
be  portrayed  may  readily  be  brought  into  the  cen- 
tre of  the  field  of  vision.  The  posterior  part  of  the 
apparatus  is  fastened  to  a  movable  plate,  which 
may  be  screwed  fast  on  to  the  ground-board,  at  a 
longer  or  shorter  distance  from  the  object-glass  ;  by 
which  means  the  operator  is  enabled  to  employ,  if 
need  be,  object-glasses  of  different  focal  lengths. 
The  whole  apparatus  is  so  arranged,  that  it  may  be 
readily  folded  and  packed.  It  weighs  only  half  as 
much  as  a  common  camera ;  and  when  carefully 
packed  up,  occupies  only  half  the  space  taken  up 
by  the  latter. 

10 

 J 


110 


PHOTOGRAPHY. 


Instead  of,  and  even  in  preference  to  the  clotli 
or  caoutchouc  bag  camera,  one  of  pasteboard  may 
also  be  used,  made  in  the  same  shape  as  the  bel- 
lows of  an  accordion.  As  this  camera  can  be 
lengthened  without  the  intervention  of  a  sliding- 
box,  it  is  peculiarly  adapted  for  copying  pictures 
in  enlarged  or  reduced  sizes.  To  do  the  former, 
and  especially  to  copy  enlarged  positive  pictures 
from  small  negatives  on  glass  or  paper,  another 
camera,  of  the  same  size  and  construction,  is  neces- 
sary, which  is  fastened  quite  tight  to  the  object- 
glass  of  the  first  camera,  so  as  to  place  the  object- 
glass  between  the  two.  The  negative  picture  to 
be  copied  is  put  into  the  frame  in  the  back  of  the 
second  camera,  which  is  then  so  placed  that  the 
direct  light  falls  through  the  negative  picture.  In 
the  frame  of  the  first  camera  is  placed  the  plate  or 
paper  intended  to  receive  the  positive  impression 
of  small  size ;  and  fitting  accordingly  in  a  limited 
compass,  may  be  taken  on  the  journey,  and  may 
then  at  leisure  be  transferred,  in  larger  size,  to  posi- 
tive plates  or  positive  paper.  The  operation  of 
copying  is  conducted  in  exactly  the  same  manner 
as  the  original  taking  of  the  negative  impression. 

The  development  of  the  positive  picture  is  ef- 
fected in  the  usual  manner. 


THE  APPARATUS. 


Ill 


119.  There  is  still  another  camera  of  a  different 
construction,  nsed  more  particularly  in  England 
and  France  for  taking  views  of  landscapes,  and  to 
which  the  name  of  "  traversing  camera"  has  been 
given.  The  peculiar  feature  of  this  camera  con- 
sists essentially  in  this,  that  with  a  comparatively 
small  and  different  object-glass,  it  produces  pic- 
tures of  considerable  size,. accuracy,  and  clearness. 
Thus,  with  an  object-glass  of  common  quality, 
views  are  obtained  fourteen  inches  long  by  four 
and  a  half  inches  wide,  and  which  are  perfectly 
clear  and  distinct  throughout,  and  embrace  a  field 
of  vision  (horizon)  of  more  than  one  hundred  and 
fifty  degrees. 

120.  The  arrangement  by  means  of  which  this 
result  is  obtained,  consists  in  the  main — -1st.  In  a 
horizontal  motion  imparted  to  the  object-glass  by 
rack- work,  and  which  causes  it  to  traverse  success- 
ively all  the  points  of  the  horizon.  2d.  In  the 
cylindrical  incurvation  which  the  paper  or  plate  is 
made  to  assume  by  means  of  a  groove  in  the  cam- 
era. As  the  paper  by  itself  would  not  retain  the 
curved  position  given  to  it,  it  is  placed  mostly  on  a 
metal  plate,  to  which  it  readily  adheres,  and  its 
incurvation  is  thus  insured  during  the  opera- 
tions :  by  this  contrivance,  objects,  at  however 


112  PHOTOGRAPHY . 

unequal  distances  from  each  other,  are  transferred 
to  the  plate  or  paper  at  the  same  focal  distance, 
and  without  displacing  the  camera.  3d.  In  a 
small  vertical  aperture  in  the  bottom  of  a  kind  of 
box,  which  accompanies  the  object-glass  in  its  mo- 
tion. This  aperture,  which  supplies  the  place  of  a 
diaphragm  that  would  occupy  a  position  in  the 
rear,  brings  to  bear  upon  an  excitable  surface  only 
the  ray  in  the  centre — those  rays  only  which  have 
no  sensible  alterations.  This  tends,  of  course,  ma- 
terially to  increase  the  distinctness  and  accuracy  of 
the  impression. 

The  position  of  the  turning  axis  of  the  object- 
glass  must  be  fixed  with  the  greatest  precision, 
otherwise  the  images  of  the  objects  towards  which 
the  apparatus  is  successively  turned,  would,  ere 
they  become  extinct  and  give  place  to  the  suc- 
ceeding ones,  move  on  the  depolished  glass,  and 
accordingly  also  on  the  plate  or  paper,  which  of 
course  would  destroy  the  clearness  of  the  image. 

To  hit  the  proper  position  of  the  axis  to  the  ob- 
ject-glass, the  tube  of  the  latter  need  simply  be 
pushed  in  more  or  less,  until  perfect  immobility  of 
the  images  is  attained. 


THE  FOCUS. 


121.  It  is  a  remarkable  fact,  and  one  which 
must  never  be  lost  sight  of  in  photographic  opera- 
tions, that  the  rajs  which  possess  the  greatest 
luminousness  do  not  likewise  exercise  the  greatest 
chemical  action.  Therefore,  even  with  the  adjust- 
ment of  the  apparatus  giving  a  perfectly  clear  and 
distinct  image  of  the  object,  and  with  the  most  rig- 
orously exact  placing  of  the  photographic  plate  or 
paper,  there  are  still  certain  accessory  conditions 
required  to  obtain  a  perfectly  correct  impression. 

The  rainbow  colors  of  the  white  ray,  refracted 
through  the  prisma,  are  seen  side  by  side  on  the 
surface  on  which  they  are  thrown :  now  in  the 
camera  obscura,  these  colors  or  rays  lie,  properly 
speaking,  behind  one  another,  and  cover  each 
other,  so  that  they  appear  to  the  eye  as  one — coin- 
ciding all  of  them  in  the  yellow  ray,  as  the  most 
intense  of  them  ;  it  is  accordingly  to  this  ray  that 
the  optical  focus  of  the  camera  obscura  is  adjusted. 
10* 


114 


PHOTOGRAPHY. 


But  the  yellow  ray  is  not  the  one  possessed  of  the 
most  energetic  chemical  action  ;  it  is  the  violet 
ray  in  which  the  chemical  force  and  influence  of 
light  chiefly  resides :  the  plate  or  paper  intended 
for  the  reception  of  the  image,  must  accordingly 
be  placed  in  the  focus  of  the  latter  ray.  Is  ow,  as 
the  length  of  each  ray  depends  partly  on  the  radius 
of  the  curvature  of  the  lenses,  partly  on  the  refrac- 
tive power  of  the  vitreous  mass,  and  partly  also  on 
the  distance  of  the  object  from  the  object-glass,  it 
follows  that  every  object-glass  must  be  specifically 
tried  and  tested  to  determine  the  difference  be- 
tween the  optical  and  chemical  focus. 

122.  In  non-achromatic  lenses,  the  point  of  con- 
veyance of  the  violet  rays,  and  accordingly  the 
chemical  focus,  lies  usually  nearer  to  the  object 
than  the  optical  focus,  which  difference  decreases, 
however,  in  proportion  to  the  distance  of  the  object 
from  the  apparatus.  In  this  case,  therefore,  the 
camera  must  be  shortened,  which  is  effected  most 
simply,  by  moving  the  object-glass  backwards. 

But  the  case  is  different  with  achromatic  lenses ; 
here  no  general  rule  can  be  laid  down,  but  every 
object-glass  must  be  submitted  to  a  separate  care- 
ful trial.  Various  apparatus  and  contrivances  have 
been  devised  to  determine  the  chemical  focus  of  an 


I  -  - 

THE  FOCUS.  115 

object-glass ;  but  the  simplest  and  easiest  way  of 
I    all,  is  the  following,  recommended  by  Professor 
Yarrentrap  : 

123.  Place  nine  books,  with  printed  titles  on  the 
back,  perpendicularly  side  by  side,  at  a  certain 
distance  from  the  object-glass,  in  such  a  manner 
that  the  second  stands  an  inch  further  back  than 
thevnrst,  the  third  than  the  second,  the  fourth  than 
;    the  third,  and  so  on  for  the  rest.    Place  and  ad- 
I    just  the  apparatus  so  that  you  see  the  titles  on  the 
I    backs  of  the  books  reflected  in  the  glass  plate,  with 
the  printing  on  the  back  of  the  fifth  in  the  row 
appearing  the  most  distinct  in  the  nine,  which  may 
be  readily  and  accurately  discerned.    ISTow,  take  a 
picture  with  the  apparatus  so  adjusted,  and  with- 
out displacing  it.    The  degree  of  accuracy  and 
distinctness  possessed  by  the  picture  will  enable 
you  to  fix  upon  the  proper  adjustment  of  the 
apparatus.     Opticians  have  indeed  endeavored  to 
supply  object-glasses  through  which  all  the  rays 
should  converge  in  one  point ;  in  this  they  have, 
j     however,  succeeded  only  for  certain  distances. 

121.  There  is  another  way  of  arranging  the  mat- 
ter, viz.,  by  employing  glasses  that  intercept  those 
rays  of  which  the  chemical  action  is  but  little  ener- 
getic ;  or,  in  other  terms,  those  rays  which  coun- 


116 


PHOTOGRAPHY. 


teract  the  chemical  effects  of  the  violet  ray ;  the 
principal  among  these  rays  is  the  yellow.  True, 
this  means  involves  a  certain  loss  of  light,  which 
however  is  amply  compensated  by  the  increased 
energy  of  the  chemical  action,  and  the  greater  cer- 
tainty in  the  performance  of  the  process. 

As  it  is,  however,  rather  dimcnlt  to  procure 
glasses  of  the  above  kind,  another  way  still  may  be 
recommended,  namely,  to  place  before  the  object- 
glass  a  very  thin  violet-colored  glass,  ground  to 
exactly  the  same  curvature  as  the  object-glass. 

This  contrivance,  which  fully  answers  the  pur- 
pose, may  be  readily  applied  to  object-glasses  of 
all  kinds. 


THEORY  OF  THE  PHOTOGRAPHIC  PHENOMENA. 


125.  If  we  inquire  the  nature  of  the  action  of 
light  in  the  production  of  the  photographic  phe- 
nomena, we  find  that  the  effects  produced  arise  from 
the  decomposing  action  which  light  exercises  upon 
metallic  compounds,  tending  to  reduce  them  to  the 
metallic  state.  In  the  case  of  iodized  silver  plates, 
the  following  appears  to  us  the  rational  explana- 
tion of  the  phenomena  observed. 

The  iodine  of  silver  formed  on  the  plate  in  the 
iodide-box,  is  reduced  by  the  action  of  the  lumi- 
mous  rays  to  subiodide — the  liberated  iodine  being 
again  absorbed  by  the  plate.  This  reduction  is 
most  considerable  in  the  most  strongly  illuminated 
parts  ;  in  the  less  illuminated  parts,  it  is  much  less 
marked  ;  and  in  the  darkest  parts  the  iodide  of  sil- 
ver is  hardly  affected  at  all.  Now,  upon  the  subse- 
quent contact  of  the  mercurial  fumes  with  the  sur- 
face of  the  plate,  the  mercury  combines  with  the 


118 


PHOTOGRAPHY. 


iodine  of  the  iodide  of  silver,  forming  subiodide  ol 
mercury,  with  a  corresponding  reduction  of  silver 
to  the  metallic  state.  The  quantity  of  the  subiodide 
of  mercury  so  formed,  is  greatest  in  the  shaded 
parts,  where  the  iodide  of  silver  is  left  almost  in- 
tact ;  less  in  the  parts  feebly  affected  by  the  lumi- 
nous rays  ;  and  least  in  the  parts  where  the  action 
of  the  light  has  been  strongest.  As  regards  the 
shaded  parts,  the  chemical  action  stops  here ;  but 
the  case  is  different  with  the  parts  previously  acted 
upon  by  the  luminous  rays.  In  these  latter  parts, 
the  subiodide  of  mercury  formed  coming  into  con- 
tact with  the  subiodide  of  silver,  a  double  decom- 
position ensues  :  trie  subiodide  of  mercury  separates 
into  two  parts,  of  which  one  combines  with  the 
iodine  of  the  subiodide  of  silver,  and  with  the 
iodine  of  the  other  part,  forming  iodide  of  mer- 
cury ;  the  reduced  silver  and  the  reduced  mer- 
cury amalgamating  and  settling  on  the  plate.  The 
picture  accordingly  makes  its  appearance  first  in 
the  lightest  parts,  since  the  quantity  of  mercury 
absorbed  is  the  greater  the  richer  the  parts  are  in 
subiodide  of  silver.  In  the  most  shaded  parts,  on 
the  other  hand,  where  iodide  of  silver  alone  is 
offered  to  the  mercurial  fumes,  there  can  be  formed 
only  a  more  or  less  dark  film  of  subiodide  of  mer- 


THEORY  OF  TILE  PHOTOGRAPHIC  PHENOMENA.  119 


cury,  mixed  with  metallic  silver  ;  which  latter  sub- 
stance, being  in  a  state  of  most  minute  division, 
exhibits  a  black  tint.  But  between  these  two  ex- 
tremes of  the  deepest  shadow  and  the  strongest 
light,  are  seen  the  semi-tints  of  the  object  depicted  ; 
and  these  semi-tints  again  are  lighter  or  darker  in 
the  different  parts  of  the  picture,  in  proportion  to 
1  the  depth  of  the  film  of  subiodide  of  silver  respec- 
tively covering  the  several  parts,  and  accordingly 
in  proportion  as  the  iodide  has  been  acted  upon 
more  or  less  vigorously  by  the  luminous  rays ;  and 
thus  we  find  also,  after  the  exposure  of  the  plate  to 
the  mercurial  fumes,  that  the  shaded  parts,  being 
covered  with  iodide  of  mercury  and  metallic  silver, 
look  black  or  greenish  ;  whereas  the  lightest  parts 
look  reddish,  from  the  presence  on  them  of  an 
alloy  of  silver  and  mercury,  in  invisible  particles, 
covered  with  a  film  of  iodide  of  mercury.  Upon 
washing  the  plate  afterwards  with  a  solution  of 
hyposulphite  of  soda,  the  iodide  of  mercury  is  dis- 
solved ;  the  subiodide  being  decomposed  at  the 
same  time  into  iodide,  which  is  then  also  dissolved, 
and  metallic  mercury  remains  on  the  plate.  The 
white  parts  of  the  picture  are  accordingly  consti- 
tuted by  the  alloy  of  mercury  and  silver  deposi- 
ted on  the  plate,'  and  are  the  more  vivid  the  more 


120 


PHOTOGRAPHY. 


copiously  this  alloy  has  been  deposited ;  the  dark 
parts,  on  the  other  hand,  are  formed  by  deposits  of 
most  minutely  divided  metallic  silver.  The  pro- 
duction of  photographic  pictures  on  paper  or  glass, 
is  likewise  the  result  of  the  decomposition,  by  the 
agency  of  light,  of  the  metallic  compounds  forming 
the  impressionable  surface ;  of  this  fact,  anybody 
may  convince  himself  by  the  following  simple  ex- 
periment : 

126.  Take  a  piece  of  paper,  prepared  with  chlo- 
ride of  ammonium  and  nitrate  of  silver,  and  put  it, 
together  with  a  little  potassium,  into  a  perfectly 
dry  glass  tube  ;  seal  this  hermetically,  and  leave  it 
about  twenty-four  hours  in  the  dark,  to  give  time 
for  the  oxygen  of  the  air  in  the  tube  to  combine 
with  the  potassium.  Place  the  tube  now  in  sun- 
light :  after  a  few  hours  you  will  find  that  the 
paper  has  acquired  a  black  tint,  though  not  of  the 
same  intensity  as  another  piece  of  the  same  paper, 
which  has  been  exposed  for  a  much  shorter  time 
in  the  open  air. 

If  you  now  open  a  glass  under  a  solution  of  am- 
monia, you  will  not  indeed  detect  any  free  chloride 
in  it ;  however,  if  you  examine  the  potassa  salt  in 
the  glass,  you  will  find  that  it  is  the  hydrochlorate, 
— an  evident  proof  that  hydrochloric  acid  must 


THEOEY  OF  THE  PHOTOGRAPHIC  PHENOMENA.  121 

have  been  liberated  from  the  paper,  and  have  com- 
bined with  the  alkali  metal. 

127.  The  several  processes  of  decomposition  and 
combination  which  have  taken  place,  may  be 
briefly  stated  as  follows  :  The  paper  having  been 
prepared  with  chloride  of  ammonium  and  nitrate 
of  silver,  we  have  in  it — 

H  CI  Az  H3  +  Az  O5  Ag  0  =  CI  Ag  +  Az  O5  Az  W  +  HO. 

128.  There  are  accordingly  contained  in  the 
paper,  nitrate  of  ammonia,  chloride  of  silver,  and 
water ;  jmd  besides  these  substances,  a  little  free 
nitrate  of  silver,  as  has  been  intimated  already  on 
a  former  occasion.  Under  the  influence  of  the 
solar  rays,  the  chloride  of  silver  is  decomposed, — 
the  liberated  chlorine  probably  combining  with  the 
hydrogen  of  the  decomposed  water,  and  forming 
hydrochloric  acid  with  it;  whilst  the  potassium 
combines  with  a  portion  of  the  liberated  oxygen  of 
water,  forming  potassa;  which  again  combines 
with  the  hydrochloric  acid,  to  form  hydrochlorate 
of  potassa  ;  the  liberated  silver  of  the  chloride  com- 
bines with  the  other  portion  of  the  oxygen,  to  form 
oxide  of  silver. 

129.  The  liberation  of  the  chlorine  may  be 
equally  demonstrated  by  another  very  simple  ex- 

11 


122 


PHOTOGRAPHY. 


periment :  Put  a  little  pure  chloride  of  silver  into 
a  bent  glass  tube,  closed  at  one  end,  and  confine 
fee  other  end  under  water ;  expose  the  chloride  in 
the  tube  to  light,  taking  care  to  shake  the  tifbe 
occasionally,  in  order  that  the  whole  of  the  chlo- 
ride may  be  brought  under  the  influence  of  that 
agent.  As  soon  as  the  chloride  of  silver  begins  to 
acquire  a  black  tint,  the  water  will  be  seen  to  rise 
in  the  tube.  When  the  whole  of  the  chloride 
has  become  black,  add  a  few  drops  of  solution 
of  nitrate  of  silver  to  the  water,  when  the  for- 
mation of  a  precipitate  of  chloride  of  silver  will 
at  once  demonstrate  the  presence  of  chlorine  in 
the  water. 

This  simple  experiment  sufficiently  shows  that 
the  chloride  of  silver  suffers  decomposition  under 
the  influence  of  light, — chlorine  being  set  free, 
and  the  reduced  silver  combining  with  oxygen 
instead. 

130.  The  same  explanation  of  the  process  applies 
equally  to  the  iodide  and  bromide,  and  the  other 
salts  of  silver.  The  use  of  gallic  acid  to  develop 
the  latent  image,  rests  upon  the  great  affinity  of 
that  acid  for  oxygen,  by  virtue  of  which  it  decom- 
poses the  salts  of  silver ;  properly  speaking,  there- 
fore, this  acid  simply  serves  to  complete  what  the 


THEORY  OF  THE  PHOTOGRAPHIC  PHENOMENA.  123 

light  has  already  begun.  The  action  of  the  light 
has  tended  already  to  loosen  the  connection  be- 
tween the  component  elements  of  the  silver  salt, 
in  the  parts  touched  by  the  luminous  rays :  in  these 
parts,  therefore,  the  gallic  acid  readily  succeeds  in 
reducing  the  silver  to  the  metallic  state — the  mi- 
nutely divided  reduced  silver  exhibiting  a  black 
tint. 

In  the  parts  that  have  not  been  acted  upon  by 
the  light,  on  the  other  hand,  the  silver  salt  has  re- 
mained unaltered;  and  the  gallic  acid  cannot, 
therefore,  effect  the  separation  of  metallic  silver 
here  so  rapidly  as  in  the  parts  impressed  by  the 
light.  ISTow,  upon  treating  these  pictures  after- 
wards with  hyposulphite  of  soda,  the  unaltered  salt 
readily  dissolves  in  this  agent,  and  is  thus  re- 
moved ;  whereas,  the  separated  silver-,  is  but  very 
little  affected,  and  remains  in  the  substance  of  the 
paper  in  a  state  of  minute  division ;  the  picture 
appears  accordingly  negative  (that  is,  if  produced 
in  the  camera  in  the  usual  manner).  Instead  of 
gallic  acid,  other  substances  that  have  a  strong 
affinity  for  oxygen,  such  as  hyposulphite,  sulphite, 
and  hyponitrate  of  protoxide  of  iron,  may  be  used 
with  the  same  result ;  also  the  alcoholic  solution  of 
many  ethereal  oils,  more  especially  of  the  oil  of 


124: 


PHOTOGKAPHY. 


clones  {oleum  caryojphyllovum),  and  of  cinnamon 
{oleum  cinnamomi) ;  these  latter,  however,  act 
much  more  slowly  than  the  other  substances 
named. 

131.  In  the  case  of  the  salts  of  iron,  the  impres- 
sion produced  by  the  decomposing  action  of  the 
light,  is  brought  out  most  fully  and  clearly  by 
subsequent  treatment  with  ferricyanide  of  potas- 
sium. 

132.  "We  give  a  few  practical  hints  on  the  proper 
selection  and  arrangement  of  the  locale  in  which 
photographic  operations  may  best  be  performed, 
and  on  the  proper  posture,  attitude,  and  dress  of 
persons  who  wish  to  have  their  portraits  taken 
with  the  photographic  apparatus. 

Photographic  portraits  are,  of  course,  always 
taken  best  in  the  open  air.  However,  as  it  is 
not  at  all  times  feasible  to  do  so,  the  photo- 
graphic artist  must  select  and  suitably  arrange  an 
appropriate  apartment  for  the  purpose.  It  need 
hardly  be  remarked  here,  that  this  apartment  must 
be  as  light  as  it  is  possible  to  get  it ;  in  fact,  the 
most  suitable  is  a  glass  house,  standing  in  an  open 
ground,  or  erected  on  the  top  of  a  building.  But 
here,  again,  every  one  has  not  the  means  at  his 
command  to  have  a  structure  of  the  kind  erected 


THEORY  OF  THE  PHOTOGRAPHIC  PHENOMENA.  125 

in  an  appropriate  spot.  Most  photographic  artists 
must  content  themselves  with  the  choice  of  a  well- 
lighted  apartment,  if  possible  with  a  skylight.  A 
room  receiving  the  light  from  the  northwest,  is 
preferable  to  others. 

The  walls  should  be  painted  of  a  light  blue, 
which  will  tend  to  diffuse  a  mild,  uniform  light 
throughout  the  apartment.  In  the  case  of  a 
glass  house,  the  light  may  be  regulated  in  the 
same  manner  by  means  of  light-blue  curtains. 
This  contrivance  has  another  beneficial  effect ; 
namely,  it  excludes  those  luminous  rays  which 
are  least  effective  in  a  photographic  point  of 
view. 

As  regards  the  proper  attitude  of  the  person  sit- 
ting for  the  portrait,  this  must  of  course  be  left,  in 
a  measure,  to  the  individual  judgment  and  taste  of 
the  artist.  However,  a  few  hints  on  this  subject 
may  not  prove  unwelcome. 

133.  The  posture  of  the  person  sitting  for  the 
-  portrait,  should  be  easy  and  unconstrained ;  the 
feet  and  hands  neither  projecting  too  much,  nor 
drawn  too  far  back  ;  the  eyes  should  be  directed  a 
little  sideways  above  the  camera,  and  fixed  upon 
some  object  there,  but  never  upon  the  apparatus, 
since  this  would  tend  to  impart  to  the  face  a  dolor- 
11* 


126 


PHOTOGKAPHY. 


oils,  dissatisfied  look.  Stout  persons  should  be 
placed  at  a  certain  distance  from  the  apparatus, 
turning  towards  it  a  little  sideways ;  whilst  people 
of  slender  make  should  be  made  to  sit  full  in  front 
and  nearer  the  apparatus.  Long  arms  and  legs 
require  drawing  back  a  little.  The  hands  should 
rest  easy  on  the  lap,  neither  too  high  nor  too  low  ; 
or  one  hand  may  be  placed  on  the  table,  the  other 
holding  a  book  or  some  other  object.  A  thick 
hand  should  show  the  thumb  in  the  foreground, 
with  the  fingers  bent  a  little  inward  ;  a  long  hand 
had  better  show  the  back ;  a  hand  of  handsome 
shape,  neither  too  long  nor  too  short,  should  show 
full  two-thirds,  with  the  fingers  easily  and  gracefully 
hanging  down.  A  slight  lateral  inclination  of  the 
body  forward  will  generally  produce  a  good  effect. 
In  the  case  of  ladies,  a  shawl  or  boa,  or  similar 
article  of  dress,  thrown  lightly  over  the  shoul- 
ders, and  arranged  in  a  manner  to  hide  some 
defect,  and  to  properly  distribute  light  and 
shadow,  will  mostly  tend  to  produce  a  pleasant 
impression. 

Of  a  full  round  face,  with  large  mouth,  small 
eyes,  and  small  nose,  the  portrait  should  be  taken 
in  half  profile,  so  as  to  show  one  side  of  the  face 
in  full,  with  very  little  of  the  other  side. 


THEORY  OF  THE  PHOTOGRAPHIC  PHENOMENA.  127 

A  moderately  full  face,  with  aquiline  nose,  and 
handsome  mouth  and  eyes,  should  be  taken  in 
three-fourths  profile  ;  a  countenance  with  strongly 
marked  features  full  in  front. 

The  selection  of  a  proper  background  for  the 
picture,  is  also  a  matter  of  some  importance.  In 
some  cases,  a  landscape  will  give  a  most  pleasing 
background ;  in  others,  a  simple  wall  will  answer 
as  well,  or  even  better  :  the  decision  here  must  be 
left  to  the  individual  judgment  and  taste  of  the 
artist. 

If  two  persons  are  to  be  portrayed  in  the  same 
picture,  the  one  should  be  made  to  lean  lightly  on 
the  chair  of  the  other,  and  the  faces  of  both  should 
be  partly  turned  to  each  other,  as  in  conversation. 
Or  they  may  be  placed  at  a  table,  seated  opposite 
each  other,  the  one  with  the  right,  the  .other  with 
the  left  arm  laid  on  the  table,  and  the  bodies  of 
both  gently  inclined  forward  and  towards  each 
other,  as  in  conversation. 

The  arrangement  of  family  groups,  again,  must 
be  left  entirely  to  'the  judgment  of  the  artist.  Care 
should  always  be  taken,  however,  to  place  the  sev- 
eral persons  constituting  the  group,  all  at  the  same 
focal  distance. 

134.  With  respect  to  dress,  colors  and  objects  of 


128 


PHOTOGRAPHY. 


intense  illumination  should  always  be  avoided  : 
this  applies  more  particularly  to  yellow  and 
scarlet.  Plain-colored  dresses,  neither  too  light 
nor  too  dark,  give  always  the  most  pleasing  pic- 
tures. 


TO  PREPARE  PHOTOGRAPHS  FOR  COLORING. 


135.  Photographs  designed  to  be  colored  in 
water-colors,  need  no  preparation  other  than  to 
be  carefully  mounted  on  thick  Bristol  paper  with 
gum-water.  ' 

But  for  oil  painting,  they  require  to  be  mounted 
upon  millboards  or  canvas,  and  thoroughly  oiled 
previous  to  the  putting  on  of  color.  Great  care 
should  be  taken  in  pasting  them  upon  the  can- 
vas, so  that  they  may  dry  smooth  and  present  an 
even  surface.  This  may  be  done  by  smoothing 
them  over,  while  the  paste  is  wet,  with  a  soft  rag 
or  some  cotton.  Almost  any  kind  of  paste  may  be 
used  for  this  purpose,  but  the  most  convenient  is  a 
solution  of  gum-arabic,  made  very  thick. 

The  most  expeditious  method  of  preparing  pho- 
tographs for  oil-color,  is  to  saturate  the  paper  with 
megilp  (a  mixture  of  boiled  linseed  oil  and  mastic 
varnish),  after  it  has  been  mounted  and  the  paste 
become  dry.  The  color  may  be  applied  at  once, 
and  worked  into  the  megilp,  or  the  whole  allowed 
to  dry.    The  latter  will  probably  be  found  to  be 


130 


PHOTOGRAPHY. 


the  better  plan,  as  the  color  will  hold  better,  and 
work  easier  when  the  preparation  is  dry  and  hard. 
Photographs  prepared  in  this  manner  are  colored 
in  the  regular  style  of  portrait-painting,  and  re- 
quire an  artist  of  some  experience  to  do  them  suc- 
cessfully, owing  to  the  difficulty  of  preserving  the 
drawing,  &c. 

Another  and  an  easier  way,  is  what  is  called  the 
u  transparent  coloring"  (by  applying  the  color  upon 
the  back  of  the  photograph).  The  photograph  is 
first  dipped  in  linseed  oil,  then  laid  upon  a  piece 
of  glass,  and  colored  upon  the  back.  A  very  fine 
effect  is  sometimes  produced  in  this  manner ;  and 
the  operation  being  exceedingly  simple,  is  capa- 
ble of  being  performed  by  persons  of  little  or  no 
experience  in  painting.  In  this  case  the  picture  is 
not  to  be  mounted  until  painted.  A  very  excellent 
substitute  for  oil  in  preparing  photographs  for  this 
style  of  painting,  is  the  Canadian  Balsam,  which 
has  the  property  of  rendering  the  paper  very  trans- 
parent, and  dries  much  better  than  oil. 

[We  are  indebted  for  the  above  article  to  Mr. 
Estes,  an  excellent  young  artist,  of  609  Broadway, 
who  has  had  considerable  experience  in  coloring 
photographs.] 


EXPLANATIONS 

OF 

SOME  OF  THE  CHEMICAL  TERMS 

Which  occur  in  the  present  zvork  ;  intended  for  the  benefit 
of  persons  unacquainted  with  Chemistry. 


136.  Chemists  divide  bodies  into  simple  and 
compound.  The  simple  bodies  are  also  called  ele- 
ments, or  elementary  substances.  These  terms, 
however,  by  no  means  imply  that  the  bodies  so 
called  are  really  simple  or  elementary ;  bnt  simply 
that  they  appear  to  ns  so  at  the  present  time,  hav- 
ing hitherto  resisted  all  attempts  to  decompose 
them. 

The  elementary  substances  at  present  known  to 
ns,  amount  to  sixty- three  in  number.  They  are 
usually  divided  into  two  great  classes,  viz.,  metals 
and  non-metallic  bodies,  or  metalloids.  This  divi- 
sion is,  however,  entirely  arbitrary,  as  the  two 
classes  completely  merge  into  each  other.  The 


132 


PHOTOGEAPHY. 


class  of  metalloids  comprises  fifteen  elementary 
bodies ;  however,  in  the  present  work  we  have 
given  only  thirteen  of  them,  viz.,  Arsenic,  Boron, 
Bromine,  Carbon,  Chlorine,  Fluorine,  Hydrogen, 
Iodine,  Nitrogen,  Oxygen,  Phosphorus,  Selenium, 
and  Sulphur.  The  class  of  metals  comprises 
forty-seven  simple  bodies,  of  which  we  have  only 
given  twenty-four,  viz.,  aluminium,  antimony,  ba- 
rium, bismuth,  calcium,  chromium,  cobalt,  cop 
per,  gold,  iron,  lead,  magnesium,  manganese, 
mercury,  molybdenum,  nickel,  platinum,  potas- 
sium, silver,  sodium,  strontium,  tin,  uranium,  and 
zinc. 

137.  Every  elementary  substance  is  designated 
in  chemical  notation  by  the  initial  of  its  Latin 
name  in  capital ;  or,  where  the  names  of  sev- 
eral substances  begin  alike,  by  the  first  letter 
conjoined  with  a  second  small  one — the  most 
characteristic  in  the  word.  This  simple  or  com- 
pound letter-mark  is  called  the  symbol  of  the 
substance ;  it  designates  not  only  the  substance 
in  the  abstract,  but  represents  one  equivalent 
of  it. 

Thus,  e.  g.)  Hg  (from  the  Greek  hydrargyrum) 
represents  one  equivalent  of  mercury ;  Fe  (from 
the  Latin  ferrum),  one  equivalent  of  iron  ;  O,  one 


EXPLANATIONS  OF  CHEMICAL  TEEMS.  133 

equivalent  of  oxygen ;  H,  one  of  hydrogen ;  Ca, 
one  of  calcium,  &c. 

The  compound  bodies  result  from  the  union  of 
two  or  several  elementary  substances.  The  com- 
binations of  metals  with  each  other  are  called 
alloys ;  or,  where  mercury  is  one  of  the  constituent 
elements,  amalgams.  The  metalloids  combine 
with  each  other,  and,  with  the  metals,  forming 
bases,  acids,  and  salts.  Thus,  for  instance,  the 
metalloid  chlorine  combines  with  hydrogen,  form- 
ing the  well-known  muriatic  acid,  which  is  more 
commonly  called  by  chemists  hydrochloric  acid ; 
chlorine  combines  also  with  the  metal  sodium, 
forming  common  salt  (chloride  of  sodium)  ;  oxygen 
combines  with  the  metal  potassium,  forming  the 
well-known  alkaline  base,  potassa,  &c.  The  com- 
bination of  bases  with  acids,  gives  rise  also  to 
the  formation  of  salts ;  thus,  for  instance,  sul- 
phuric acid,  a  compound  of  sulphur  and  oxygen, 
forms  with  the  base  potassa  a  salt,  the  sulphate 
of  potassa.  Two  salts  frequently  combine  with 
each  other,  forming  what  chemists  call  double- 
salts  ;  thus,  for  instance,  the  sulphate  of  alumina 
and  the  sulphate  of  potassa  form  a  double-salt, 
known  as  the  double  sulphate  of  alumina  and 
potassa. 


134 


PHOTO  GE  APH  Y . 


138.  The  chemical  union  of  bodies  is  governed 
and  regulated  by  certain  fundamental  laws,  called 
the  laws  of  combination,  and  which  may  be  briefly 
stated  as  follows : 

(1)  All  chemical  compounds  are  definite  in  their 
nature,  the  ratio  of  the  elements  being  constant ; 
in  other  terms,  the  same  chemical  compound  in- 
variably contains  the  same  elements,  combined  in 
unvarying  proportions. 

(2)  Where  a  body  is  capable  of  combining  with 
another  in  several  proportions,  these  proportions 
bear  a  simple  relation  to  each  other.  Thus  one 
equivalent  of  A  will  combine  with  1,  2,  3,  4,  5, 
equivalents  of  B ;  or  two  of  A  with  1,  2,  3,  4,  5, 
6,  7,  of  B  ;  or  three  of  A  with  5,  7,  of  B ;  and 
so  on.  This  law,  which  was  first  advanced 
by  Dalton,  in  1807,  is  called  the  law  of  multi- 
ple proportions.  The  most  simple  proportions 
occur  most  frequently :  we  generally  find  be- 
tween the  component  elements  of  compound  bod- 
ies, the  proportions  of  1  to  1,  of  1  to  2,  of  1 
to  3,  of  1  to  4,  of  1  to  5  ;  or  of  2  to  3,  of  2  to  5, 
of  2  to  7. 

3.  The  quantities  in  which  two  bodies  unite 
with  a  third  body,  express  also  the  relative  pro- 
portions in  which  they  unite  with  each  other,  pre- 


EXPLANATIONS  OF  CHEMICAL  TEEMS.  135 

suming  always,  of  course,  that  they  do  unite  with 
each  other.  For  instance,  hydrogen  combines  with 
oxygen  in  the  proportion  of  1  part  (by  weight)  of 
the  former  to  8  parts  (by  weight)  of  the  latter ; 
chlorine  combines  with  oxygen  in  the  proportion  of 
3  5* 5  parts  (by  weight)  of  the  former  to  8  parts  (by 
weight)  of  the  latter :  chlorine  combines  accord- 
ingly with  hydrogen  in  the  proportion  of  35" 5  (by 
weight)  of  the  former  to  1  part  (by  weight)  of  the 
latter.  As  oxygen  has  a  most  extensive  range  of 
affinity,  and  very  great  powers  of  combination, 
uniting  in  fact  with  all  the  elementary  substances, 
with  the  single  exception  of  fluorine,  and  as  its 
compounds  are  susceptible  of  the  most  rigid  and 
exact  analysis,  this  body  has  been  chosen  by 
chemists  as  the  starting  substance  in  the  construc- 
tion of  the  table  of  chemical  equivalents.  The 
number  assigned  to  the  equivalent  of  the  starting 
substance  is  entirely,  arbitrary.  Continental  chem- 
ists usually  assign  the  number  100  to  the  equiva- 
lent of  oxygen,  12*5  to  that  of  hydrogen,  443*75  to 
that  of  chlorine ;  but  it  will  be  readily  seen  that 
the  relative  ratio  remains  the  same  :  100  is  to  12*5 
as  8  is  to  1,  to  443*75  as  8  is  to  35*5.  8  has  been 
chosen  here  as  the  more  convenient  figure  of  the 
two,  and  because  it  is  the  proportion  in  which  oxy- 


136 


PHOTOGKAPIIY. 


gen  combines  with  one  part  (by  weight)  of  hydro- 
gen to  form  water,  supplying  ns  thus,  in  the 
equivalent  of  the  hydrogen,  with  a  unity  of  which 
the  equivalents  of  all  other  simple  substances 
should  be  integer  multiples,  according  to  a  theory 
advanced  by  a  most  eminent  English  chemist 
(Prout).  A  glance  at  the  table  of  equivalents  of 
elementary  bodies  will,  however,  suffice  to  show 
that,  in  the  present  state  of  our  knowledge,  at  all 
events,  this  hypothesis  is  not  sufficiently  supported 
to  justify  its  admission. 

(4)  The  combining  quantity  or  proportion  of  a 
compound  is  the  sum  of  the  combining  quantities 
of  its  components.  Let  us  take,  for  instance,  chlo- 
ride of  sodium.  The  equivalent  of  chlorine  is  35-5, 
that  of  sodium  23  ;  the  combining  proportion  or 
equivalent  of  the  chloride  of  sodium  is  there- 
fore 58-5. 

139.  Most  of  the  compounds  which  the  metal- 
loids form  with  the  metals,  are  now  generally 
designated  in  chemical  nomenclature  as  ides  •  but 
many  of  them  were  formerly,  and  are  still  by  some 
chemists,  designated  as  urets.  The  termination 
ide  (or  uret)  is  substituted  for  the  termination  of 
the  name  of  the  metalloid,  and  the  preposition  of 
interposed  between  this  and  the  unaltered  name  of 


EXPLANATIONS  OF  CHEMICAL  TERMS.  137 

the  metal.  Thus,  for  instance,  the  compound 
formed  by  the  union  of  the  metalloid  chlorine  with 
the  metal  sodium,  is  called  chloride  of  sodium ; 
the  compound  formed  by  oxygen  with  silver,  is 
called  oxide  of  silver,  &c,  &c. 

As  has  already  been  stated,  bodies  may  combine 
with  each  other  in  several  proportions,  bearing  a 
definite  simple  relation  to  each  other. 

Thus  oxygen  combines  with  manganese  in  six 
different  proportions,  viz.,  1  to  1,  3  to  2,  2  to  1, 
4  to  3,  3  to  1,  and  7  to  2.  The  first  compound 
(1  of  oxygen  to  1  of  manganese)  is  called  the  pro- 
toxide of  manganese  ;  the  second  (3  of  O  to  2  of 
Mn),  the  sesquioxide;  the  third  (2  of  O  to  1  of 
Mn),  the  deutoxide  or  binoxide  ;  the  fourth  being, 
in  reality,  a  compound  of  the  protoxide  with  the 
sesquioxide,  is  properly  called  proto-sesquioxicle ; 
the  fifth  compound  of  oxygen  with  manganese 
(Mn  O3),  having  acid  properties,  i.  combining 
with  bases  to  form  salts,  is  termed  manganic  acid. 
The"  composition  of  this  acid  would  be  indicated  by 
the  term  teroxide  of  manganese.  The  term  oxide, 
however,  is  not  applied  to  bodies  having  acid 
properties ;  thus  we  do  not  say,  for  instance,  ter- 
oxide of  arsenic,  or  pentoxide  of  arsenic,  but  arse- 
nious  acid  for  the  former,  and  arsenic  acid  for  the 
12* 


138 


PHOTOGRAPHY. 


latter  ;  and  the  sixth  compound  (Mn2  O7)  is  called 
hypermanganic  or  permanganic  acid.  Compounds 
containing  less  than  one  equivalent  of  oxygen  to 
one  equivalent  of  metal,  are  called  suboxides ; 
thus  Cu2  O  (two  equivalents  of  copper" to  one  of 
oxygen)  is  called  suboxide  of  copper.  The  same 
rules  hold  generally  good  also  in  the  nomenclature 
of  compounds  of  oxygen  with  the  metalloids,  and 
in  those  of  sulphur  and  other  metalloids  with  the 
metals  and  with  each  other.  Most  of  the  metal- 
loids form  acids  with  oxygen,  as  chlorine,  iodine, 
bromine,  sulphur,  phosphorus,  nitrogen,  carbon, 
selenium,  boron,  silicon,  arsenic,  tellurium ;  some 
form  acids  with  hydrogen,  as  chlorine,  iodine,  bro- 
mine, fluorine,  sulphur :  these  latter  acids  are 
called  respectively  hydrochloric,  hydriodic,  hydro- 
bromic,  hydrofluoric,  hydrosulphuric  acids.  With 
regard  to  the  neutral  or  basic  compounds,  wdiich 
the  metalloids  form  among  themselves,  the  ter- 
mination ide  is  always  given  to  the  oxygen,  where- 
ever  that  body  forms  one  of  the  constituents. 
Chlorine  follows  next  after  oxygen  in  this  respect ; 
thus  we  say,  chloride  of  iodine,  of  sulphur,  of  nitro- 
gen. Bromine  follows  next  after  chlorine  (bro- 
mide of  iodine).    The  next  is  fluorine  (fluoride  of 


EXPLANATIONS  OF  CHEMICAL  TERMS.  139 

silicon).  After  this  comes  sulphur  (sulphide  of 
arsenic,  sulphide  of  carbon). 

The  compounds  which  phosphorus,  carbon,  ar- 
senic, selenium,  form  with  hydrogen,  are  called 
respectively,  phosphuretted,  carburetted,  arseniu- 
retted  (or  arsenietted),  seleniuretted  hydrogen. 


APPENDIX. 


WEIGHTS  AND  MEASURES. 

There  are  three  standards  of  weights  recognized  in  the 
United  States  and  Great  Britain,  viz.,  the  Avoirdupois, 
the  Troy,  and  the  Apothecaries'. 

It  would  be  a  most  desirable  result  if  scientific  societies 
would  select  from  the  various  standards  one  complete 
standard  of  weights,  and  one  of  fluid  measures,  and  sanc- 
tion them  by  their  political  influence  to  the  exclusion  of 
all  others.  Modern  international  commercial  intercourse 
demands  this  important  innovation. 

The  cosmopolite,  the  scientific  man,  the  man  of  com- 
merce, and  the  people,  would  all  alike  be  relieved  from 
much  embarrassment,  mistakes,  and  of  the  necessity  of  re- 
learning  a  long  catalogue  of  school-day  lessons  of  the 
utmost  importance. 

Avoirdupois  Weight. 

This  is  the  one  usually  employed  in  buying  and  selling 
such  articles  as  are  measured  by  weight,  and  is  also  em- 


142  APPENDIX. 

ployed  by  apothecaries,  but  not  in  the  dispensing  of  medi- 
cine. 

Troy  Grains. 

1  dr.   =  27-34375 

16   "  =       1  oz.    =  4375 

256   "  =     16  "  =     1  lb.  =  7000' 

3584   "  =    224  "  =   14  "  =   1  stone  =  98000- 

28672  «  =  1782  "  =  112  u  s=  8  "  =  1  cwt.  -  =  784000* 
473440   "  =  35840  "  =2240  «  =160    "   =20    "    =1  ton=15680000- 

In  this  country,  most  bulky  articles  are  weighed  by  the 
short  ton,  2000  pounds. 


Troy  Weight. 

This  is  used  in  the  exchange  of  gold,  silver,  platina,  and 
precious  stones. 

* 

24  grains  =    1  pennyweight 
480    "     =  20         "        =1  ounce. 
5760    "    =240         "        =12     "     =1  pound. 

Relative  proportions  between  the  Troy  and  Avoirdupois 
Weights. 

1  pound  Troy  is  equal  to  0'822857  pound  avoirdupois, 
or  13  ounces,  2  drachms,  1  scruple,  8*7  grains,  or  13 
ounces,  148*7  grains. 

1  ounce  troy  is  equivalent  to  1  ounce,  1  drachm,  1  scru- 
ple, and  6*225  grains  avoirdupois. 

1  pound  avoirdupois  is  equal  to  1*215277  pound  troy, 
or  1  pound,  2  ounces,  4  drachms,  and  2  scruples. 


WEIGHTS  AND  MEASURES. 


143 


1  ounce  avoirdupois  is  equal  to  7  drachms  17*5  grains. 
144  pounds  avoirdupois  are  equivalent  to  175  pounds 
troy. 

175  ounces  troy  are  equivalent  to  192  ounces  avoirdu- 
pois. 

Apothecaries'  Weight. 
Used  in  compounding  and  dispensing  of  medicines. 

20  grains  =    1  scruple. 
60    "     —    3     «     =  1  drachm. 
490    "    =  24     "     =  8     "      =  1  ounce. 
5760    "     =288     «     =96     "      =12     «    =1  pound. 

Marks— gr.  3,  3,  %  lb. 


Dublin  Weights,  (Adopted  1850.) 

18-22  grains  =    1  scruple. 
54-68     "    =    3     "      =1  drachm. 
437-5      "    =  24     «     =8      "     =  1  ounce. 
7000-       "    =384     «      =123      «      =16     «    =1  pound. 


French  Metrical  Weights. 


Troy  Grains. 

1  milligramme   _-  -015434 

10=        1  centigramme   —  -15434 

100  =       10  =       1  decigramme    -      -      -      -      .  —  1-5434 

1000=     100=     10=      1  gramme  -  —  15.434 

10000=    1000=    100=    10=    1  decagramme    -      -  =  154-34 

100000=  10000=  1000=  100=  10=  1  hectogramme    -  =  1543-4 

1000000  =  100000  =  10000=:  1000  =  100  =  10  =  1  kilogramme  =15434. 


The  above  weights  not  being  generally  used  by  the 
French  people,  the  following  was  substituted,  in  1812,  in 


144 


APPENDIX. 


part;  but  in  1S31  a  law  was  passed  which  definitively 
abolished  the  use  of  all  other  weights  and  measures,  ex- 
cepting those  of  the  metrical  or  decimal  system,  from  and 
after  August,  1840.  The  metrical  weight,  therefore,  is 
now  the  only  one  permitted  to  be  used  throughout 
France. 

Value  of  Troy  in  Metrical  Weight. 


1  pound   =    373-202  grammes. 

1  ounce   =      3M0017  « 

1  drachm   =       3-SS7521  " 

1  scruple    -----  =       1-295840  " 

1  grain   =       0-06479201  " 

Value  of  Troy  m  Marc  Weight. 

a  pound  =  12  onces,  1  gros,  42-32  grains. 

1  ounce      -      -      -      -      r=  1"0"      953  " 

1  drachm    -      -      -      -      =  0     "     1   "     1-19  " 

1  scruple     -      -      -      -      =  0     "     0   "    24-40  " 

1  grain       -      -      -      -      =  0     "     0   "     122  " 


In  all  the  European  States,  except  in  France,*  Dublin, 
and  Turkey,  the  medicinal  pound  is  divided  into  12 
ounces. 

In  all  of  them  the  ounce  is  divided  into  8  drachms,  ex- 
cept in  Naples,  where  it  contains  10.  In  all,  the  ounce  is 
divided  into  3  scruples  ;  but  the  value  of  the  scruple  dif- 

*  In  France,  the  standard  of  weights  and  measures  is  the  same 
for  all  commercial  products,  chemicals,  medicines,  precious  metals, 
etc.,  etc.  The  French  government  prohibts,  by  penal  enactment, 
the  use  of  old  weights  and  measures. 


WEIGHTS  AND  MEASURES.  14:6 

fers.  It  is  composed  of  24  grains  at  Bologna,  Coni, 
Lucca,  Modena,  Parma,  and  Rome,  and  in  Spain,  Por- 
tugal, Tuscany,  and  Sardinia.  Of  20  grains  in  Great 
Britain  (except  in  Dublin,  where  it  is  18*22  grains),  the 
United  States,  Austria,  Bavaria,  Holland,  Poland,  and 
Sweden ;  at  Lubeck,  Naples,  Nuremberg,  and  Venice. 
Therefore  the  pound  consists  of  5760  grains  in  the  United 
States,  Great  Britain,  Austria,  Bavaria,  Holland,  Poland, 
Prussia,  and  Sweden  ;  at  Lubeck,  Naples,  and  Venice.  In 
Turkey  6400  grains.  6912  grains  in  Spain,  Portugal, 
Tuscany,  Sardinia,  Bologna,  Lucca,  Modena,  Parma,  Rome, 
and  Coni.  7000  grains  in  Dublin;  7200  grains  at  Na- 
ples. 

Wine  or  Apothecaries'  Measure. 
(Adopted  by  the  United  States  Dispensatory.) 

Cubic  Inches.  Grains  Troy, 
0-95 

—  0-2256  —  56-96 
=  1-8047  =  455-69 
=  28-875  ==  7291-11 
=  231- 


1  minim  

60  =     1  fittidrachni  .... 
480  =     8=    1  fluidounce 
7680=  123=  16  =  1  pint  .... 
61440  =  1024  =  128  =  8  =  1  gallon  (Cong, 


Imperial  Measure. 
(Adopted  by  all  the  British  Colleges.) 

Minims.  Grains  Troy.  Avoir. 

1  -      =  0-91 

60=    1  f.  drachm  =  54-7 

480=    8      «      =  1  f.  ounce  =     437-5  =1  ounce. 

9600=  160  «  =  20  "  =1  pint  -  =  8750-  =  1-25  lb. 
76800=1280      «      =160      "    =3   "  =1  gallon=  70000-  =10  lbs. 

13 


146 


APPENDIX. 


Value  of  Wine  or  Apothecaries'  Measure  in 
Imperial  Measure. 

Wine  Measure.  Imperial  Measure. 


Pints. 

Fluidounces. 

Fluidrachms. 

Minims 

1  gallon 

=  6 

13 

2 

23 

16 

5 

18 

1  fluidounce 

=  0 

1 

0 

20 

1  fluidrachm 

=  0 

0 

1 

2  5 

1  minim  - 

=  0 

0\ 

0 

104 

Value  of  Imperial  in  Wine  or  Apothecaries' 
Measure. 


Gallon. 

Pints. 

Fluidounces. 

Fluidrachms. 

1  gallon 

.  -  =1 

'K    1  - 

9 

5 

1  pint 

=  0 

1 

3 

i 

1  fluidounce 

==   0  . 

0 

0 

7 

1  fluidrachm 

-      =  0 

0 

0 

1  minim 

-      =  0 

0 

0 

0 

French  Measure  of  Capacity — Apothecaries' 
Measure. 

1  millilitre   =  16-2318  minims. 

10=       1  centilitre   =   2-7053  fl.  dr. 

100=      10=      1  decilitre   =   3-3S16  fl.  oz. 

1000=    100=     10=     1  litre  -  =  21135  pints. 

10000=   1000=   100=   10=  1  decalitre  -      -      -  =   2-6419  gallons. 

100000=  10000=  1000=  100=  10=  1  hectolitre         -  =  26-4190 

1000000=100000=10000=1000=100=10=  1  kilolitre      -  =2641900  " 


APPENDIX. 


147 


THERMOMETERS. 

The  Fahrenheit  scale  is  divided  into  180  equal  degrees 
between  the  points  at  which  ice  melts  and  water  boils ; 
then  counting  downward  32  degrees  from  the  point  of 
melting  ice  to  obtain  zero. 

The  Centigrade  thermometer  fixes  its  zero  at  the  point 
of  melting  ice,  and  the  boiling  point  of  water  at  100°,  the 
scale  being  equally  divided  between  the  two  points. 

To  reduce  Centigrade  degrees  to  those  of  Fahrenheit. 
Rule. — Multiply  by  9,  divide  the  product  by  5,  and  add  32. 

Cent.  Fahr. 

Thus,  40x9  +  5  +  32  =  104. 

To  reduce  Fahrenheit's  degrees  to  those  of  Centigrade. 
Rule. — Subtract  32,  multiply  by  5,  and  divide  by  9. 

Fahr.  Cent. 

Thus,  104  —  32  x  5  ~  9  =  40. 

To  reduce  Reaumur's  degrees  to  those  of  Fahrenheit. 
Rule. — Multiply  by  9,  divide  by  4,  and  add  32. 

Keaumnr.  Fahr. 

Thus,  32x9+4  +  32  =  104. 

To  reduce  Fahrenheit's  degrees  to  those  of  Beaumur. 
Rule. — Subtract  32,  multiply  by  4,  and  divide  by  9. 

Fahr.  Keaum. 

Thus,  104  —  32  x  4  +-  9  =  32. 

To  reduce  Beaumur' s  degrees  to  those  of  Centigrade. 
Rule.— Multiply  by  5,  and  divide  by  4. 

v  Keaum.  Cent. 

Thus,  32x5 -+4  =  40. 

To  reduce  Centigrade  degrees  to  those  of  Beaumur. 
Rule. — Multiply  by  4,  and  divide  by  5. 

Cent.  Keaum. 

Thus,  40x4  +  5  =  32. 


148 


APPENDIX. 


Table  of  the  most  important  chemical  elements,  or 
simple  bodies,  with  their  respective  symbols  and 
combining  proportions. 


EQUIVALENTS,  OK 

COMBINING  PROPORTIONS.  i 

NAME. 

SYMBOL. 

■■ 

OXYGEN=100. 

HYDROGEN— 1. 

Aluminium  - 

AL 

170'5 

13-6 

Antimony  (Stibium) 

Sb. 

1612-5 

129-0 

Arsenic   -      -      -  - 

As. 

937-5 

75-0 

Barium  - 

Ba. 

857-5 

68*6 

Bismuth  - 

Bi. 

2600-0 

208-0 

Boron  - 

B. 

136-2 

10-9 

Bromine  - 

Br. 

1000-0 

80-0 

Calcium  -      -  - 

Ca. 

250-0 

20-0 

Carbon  - 

C. 

-  75-0 

6-0 

Chlorine  - 

CI. 

443-7 

35-5 

Chromium  - 

Cr. 

335.0 

26-8 

Cobalt  - 

Co. 

368-6 

29-5 

Copper  (Cuprum)  - 

Cu. 

396-0 

31-7 

Fluorine  - 

F. 

237-5 

19-0 

Gold  (Aurum) 

Au. 

2462-5 

197-0 

Hydrogen       _      _  _ 

H. 

12-5 

1-0 

Iodine  - 

I." 

1585-0 

126-8 

Iron  (Ferrum) 

Fe. 

350-0 

28-0 

Lead  (Plumbum)  - 

Pb. 

1294-6 

103.6 

Magnesium  - 

Mg. 

150-2 

12-1 

Manganese      -      -  - 

Mn. 

344-7 

27-6 

Mercury  (Hydrargyrum) 

Hg. 

1250-0 

100-0 

Molybdenium  -      -  - 

Mo. 

575-0 

46-0 

Nickel    -      -      -  - 

Ni. 

369-3 

29-6 

Nitrogen  - 

N. 

175-0 

14-0 

Oxygen  - 

0. 

100-0 

8-0 

Phosphorus  - 

Ph. 

392-0 

31-4 

Platinum  - 

Pt. 

1236-7 

98-9 

Potassium  (Kalium) 

K. 

490-0 

39-2 

Selenium  - 

Se. 

494-0 

39-5 

Silver  (Argentum)  - 

Ag. 

1349-6 

108-0 

Sodium  (Natrium)  - 

Na. 

287-5 

23-0 

Strontium  - 

Sr. 

545-9 

43-7 

Sulphur  - 

S. 

200-0 

16-0 

Tin  (Stannum) 

Sn. 

735-3 

58-8 

Uranium  - 

U. 

742-9 

59-5 

Zinc  - 

Zn. 

406-6 

32-5 

APPENDIX. 


149 


Table  of  the  most  important  chemical  compounds 
(in  a  photographic  point  of  view),  with  their 

FORMULAE  AND  COMBINING  PROPORTIONS. 


EQUIVALENT,  OR 

NAME. 

FORMULA. 

MIXING 
PRO  PORTION. 
HYDROGEN  =  1. 

Acetate  of  Alumina 

Al2  03^A 

204.2 

"     "  baryta 

BaO,  A  -f-  HO 

136*6 

"     "    copper,  neutral 
crystallized 

CuO,  A  +  HQ 

99-7 

Acetate  of  lead,  neutral 
(sugar  of  lead) 

PbO,  A+3HO 

189.6 

Acetate  of  soda  - 

NaO,  A  +  6HO 

136*0 

Acetic  acid  j 

C.  Hq  0,.  4-  HO— A  ) 

^4  -L-L3  ^3   ]T  -L-L ^ — ( 

_i_  HO  f 

60*0 

Alcoliol  - 

C  H„  0„  4-  TTO 

55*0 

Alum,  Ammonia- 

NH*  0,  S03  +  Al2 ) 
Oj,  8S08+24HO  j 

453-2 

"  potassa- 

KO,  S08  +  A19  03>  ) 
3S03  +  24HO  J 

474-4 

Ammoniacal  gas  (spirits  of 
hartshorn) 

NH3 

17-0 

Ammonia,  solution  or  li- 
quor of 

NH3  +  #H0 

Amylum  {see  Starch)  - 

Antimoniate  of  potassa 

KO,  Sb05 

216-2 

Arseniate  of  potassa 

KO,  As05  +  2HO 

180-2 

Baryta  - 

BaO 

76-6 

Benzoic  acid 

C14H503  +  HO 

122-0 

•Biborate  of  soda  (borax) 

NaO,  2BO3-f-10HO 

190-8 

Boracic  acid,  crystallized 

B03  +  3HO 

61-9 

Bromic  acid        -      -  - 

Br05 

120-0 

Bromide  of  potassium 

KBr 

119-2 

"       "  silver 

AgBr 

188-0 

"       "  sodium 

NaBr 

103-0 

Bromiodine  - 

IBr3 

366-8 

Camphor,  Japan  -      -  - 

Cjo  H8  0 

76-0 

Carbonate  of  ammonia 

NH3,  CO, 

39-0 

( "           "        ses-  ) 
quicarbonate    -      -  j 

2NH4,0  +  3COa 

118-0 

Carbonate  of  baryta 

BaO,  C02 

98-6 

"      "  lime 

CaO,  C02 

MgO,  C02  +  3HO 

50-0 

"      "  magnesia 

69-1 

"      "     potassa  (neu- 
tral - 

KO,  C02 

69-2 

13* 


150 


APPENDIX. 


EQUIVALENT,  OK 

MIXING 

NAME. 

FORMULA. 

PROPORTION. 
HYDROGEN  =  1. 

Carbonate  of  potassa  (acid 
or  bicarbonate) 

KO,  2C02  +  HO 

100-2 

Carbonate  of  soda  (cry stall.) 

NaO,  CO^+IOHO 

143-0 

"      "     soda  (bicar- 
bonate) 

NaO,  2CO2  +  HO 

84-0 

Carbonate  of  strontia  - 

SrO,  C02 

73-7 

Carbonic  acid  - 

C02 

22-0 

Caoutchouc  - 

C8H7 

55-0 

Chlorate  of  ammonia  - 

NH4  0,  C10s 

101-5 

"      "  baryta 

BaO,  CIO5  +  HO 

161-1 

u       "  potassa 

KO,  CIO5 

122-7 

"      M  soda 

NaO,  CIO5 

106-5 

Chloric  acid  - 

pin 

i  O  0 

Chloride    of  aluminium 
(sesquichl.) 

Al2  Cl3  +  12HO 

241-7 

Chloride    of  ammonium 
(sal-ammoniac) 

NH4,  CI 

53-5 

Chloride  of  arsenic 

AsCl, 

181-5 

"       "  barium 

BaCl  +  2HO 

122-1 

"       "  cobalt 

CoCl 

65-0 

"      "   copper     (sub- ) 
chloride)  j 

Cu2  CI 

98.9 

Chloride  of  copper,  crystal-  j 
lized        -      -      -  j 

CuCl  +  4HO 

103-2 

Chloride  of  cyanogen,  ga-  } 
seous  (proto-)  j 

CyCl 

61-5 

Chloride  of  cyanogen,  solid 

(sesqui.) 
Chloride  of  gold  (terchlor.) 

Cy2  Cl3. 

158-5 

AuCl3-f  6HO 

357-5 

"       "    gold  and  sodium 

NaCl  +  AuCl3  +  6HO 

416-0 

"       v    iodine,  liquid 
(proto-)  - 

1 

IC1 

162-3 

Chloride  of  iodine,  solid 
(ter)  -      -      -  - 

J 

IC13 

233-3 

Chloride  of  iron,  proto- 

FeCl  +  4HO 

99-5 

"          "  sesqui- 

Fe2  Cl3  +  6HO 

216-5 

Chloride  of  lead,  neutral 

PbCl 

139-1 

"      "    lime  (bleach- 
ing powder 

1 

CaO,  ClO  +  CaCl 

127-0 

Chloride   of  magnesium, 
crystal.  - 

MgCl+5HO 

92-6 

Chloride   of  manganese, 
proto-  - 

1 

MnCl  +  4HO 

99-1 

Chloride   of  manganese, 
sesqui-  - 

[ 

Mn2  Cl3 

161-7 

APPENDIX. 


151 


4 


Chloride  of  mercury  (cor 
rosive  sublimate) 

Chloride  of  nickel 

"  "  and  am- 
monia (ammonio-chlo 
ride  of  nickel)  - 

Chloride  of  nitrogen  (terchl.) 
"  "  platinum,  hy- ) 
drated  bichloride     -  ) 

Chloride  of  potassium  - 
"      "  silver 
"      "    sodium  (com- ) 
mon  salt)  -      -      -  j 

Chloride  of  strontium  - 
"       "  sulphur(subchl.) 
"       "    tin,  crystalliz-  ) 
ed  proto-  ) 

Chloride  of  tin,  crystal-  [ 
lized  bichloride        -  J 

Chloroform  - 

Chromate  of  lead,  neutral  - 
"  "  potassa,  neutral 
«      "        "       acid  i 

or  bichromate  -  -  f 
Citrate  of  sesquioxide  of  iron 

"     "  sesquioxide  of) 

iron  and  ammonia  -  j 
Citrate  of  sesquioxide  off 

iron  and  potassa  -  J 
Citrate  of  sesquioxide  of  j 

iron  and  soda  j 
Citrate  of  mercury 

"  «  silver  -  -  - 
Citric  acid,  by  crystalliza-  ) 

tion  at  the  common  tern-  > 

perature  -  -  -  ) 
Citric   acid,    precipitated  j 

from  a  hot  saturated  so-  > 

lution,  and  dried  at  212°.  J 
Cobalt,  oxide  of  - 
Cotton  - 
Cyanate  of  potassa 
Cyanic  acid  - 
Cyanide  of  potassium  - 

"      "   silver - 


HgCl 

NiCl  +  lOHO 
NiCl  +  2NH3  +  HO 
NC13 

PtCl2  +  8HO 

KC1 
AgCl 

NaCl 

SrCl  +  6HO 
S2  CI 

SnCl+HO 

SnCl2  +  2HO 

Ca  HC13 
PbO,  Cr03 
KO,  Cr08 

KO,  2Cr03 


CiaH6Ou+5HO= 

=Ci 

210-0 

CM  H5  On+8HO= 

=Ci 

192-0 

CoO 

37-5 

CHO 

15-0 

KO,  CyO 

81-2 

CyO  +  HO 

43-0 

KCy 

65-2 

AgCy 

134-0 

EQUIVALENT,  OR 
MIXING 
PROPORTION. 
HYDROGEN  =  1 


— 


152  APPENDIX. 

NAME. 

FORMULA. 

EQUIVALENT,  OK 
MIXING 
PROPOETION. 
HYDROGEN  =  1. 

Cyanogen  - 
Ether  - 

Ferricyanide  of  potassium  ) 
(red  prussiate  of  potassa  j 

Ferrocyanide  of  potassium  j 
(yellow  prussiate  of  po-  > 
tassa)  ) 

Fluoride  of  ammonium 
"      "    calcium  (fluor-  ) 
spar)                     -  j" 

Fluoride  of  potassium  - 
"       "  sodium 

Formic  acid  - 

Gallic  acid,  crystallized 

Gold,  oxide  (teroxide)  of  - 

Hydrobromic  acid 

Hydrochloric  acid 

Hydrochloric   acid,  most ) 
concentrated  hydrated  j 

Hydrocyanic  acid 

Hydrofluate  of  ammonia 

Hydrofluoric  acid 

Hydriodate  of  ammonia 

Hydriodic  acid  - 

Hydrosulphuric  acid  (sul-  ) 
phuretted  hydrogen)  j 

Hyponitrate  of  protoxide  of ) 
iron  -      -      -      -  j 

Hyponitric  acid  - 

Hyposulphate  of  protoxide  ) 
of  iron  ) 

Hyposulphate  of  soda  - 

Hyposulphuric  acid 

Hyposulphurous  acid  - 

Iodate  of  ammonia 

Iodic  acid  - 

Iodide  of  ammonium  - 
"     "  iron  (sesqui-) 
"     "  potassium  - 
"     "  silver  - 
"     u  sodium 

Iron,  protoxide  of 
Sl    sesquioxide  of  - 
"    hydrated   sesqui  ox-  ) 
ideof                   -  j 

C2N  =  Cy 
C4  H50 

3KCy,  Fe2  Cy3 

2KCy,  FeCy  +  3HO 

NH4,  Fl 

CaFl 

KFl 

NaFl  _ 

C2  H03+HO=Fo  _ 

C7H2  04  +  HO  =  Ga 

Au03 

BrH 

CIH 

C1H  +  6HO 

CyH 

FIH 

NH3,  HI 
HI 

HS 
N04 

NaO,  S2  02  +  5HO 

s2o5 
s2  02 

NH4  0, 105 

I05  +  HO 

NH4,I 

Fe2 13 

KI 

Agl 

Nal 

FeO 

Fea  03 

Fe2  03  +  3HO 

26-  0 
37*0 

329-6 

211-4 

37-0 

39-0 

58-2 
42-0 
46-0 
85-0 
221-0 
81-0 
36-5 

90-5 

27-  0 

20-0 
144-8 
127-8 

17-0 

46-0 

124-0 
72-0 
48-0 
192-8 
175-8 
144-8 
436-4 
166-0 
234-8 
149-8 
36-0 
80-0 

107-0 

APPENDIX. 


153 


EQUIVALENT,  0E 

MIXING 

NAME. 

FOEMULA. 

PE0P0ETI0N. 

1  I 

HYDE0GEN  —  1. 

Lime,  hydrate  of        -  - 

CaO  +  HO 

37'0 

Malic  acid    -      -      -  - 

C4  H2  04  +  HO  =  M 

67-0 

Manganate  of  potassa  - 
u       u        a  per. 

KO,  Mn03 

98-8 

KO    Mlln  O 

158-4 

Milk  sugar  -      -      -  - 

0o4  H22  02a  +  2HO 

360*0 

Nickel,  oxide  of  - 

NiO 

87*6 

Nitrate  of  ammonia 

NH4O,  N05  +  HO 

89-0 

"     "    baryta  - 

BaO,  N06 

130-6 

"     u   sesquioxide  of 
cliromium 

Cr2  03,  3N05 

239-6 

Nitrate  of  copper 

OnO  NO* 

93.7 

"     "     sesquioxide  of) 
iron  -      -      -      -  j 

Fe2  03,  8NO5 

242-0 

Nitrate  of  lead  - 

PbO,  N05 

165-6 

"     "  mercury 

z^iigvj,  jyyjs)  -f-  xiu 

333'0 

"     "    mercury  and 
ammonia  - 

(NH3,  N05)  +  3Hg0 

395-0 

Nitrate  of  nickel  - 

NiO,  NO5+  6HO 

145-6 

"     "  potassa 

ko,'no5 

101-2 

"     u   silver  - 

As-6  NOc 

170-0 

a     "      u    and  am- 
monia     -      -  - 

AgO,N05  +  2NH3 

204-0 

Nitrate  of  soda  - 

NaO,  N05 

85-0 

"     "  strontia 

SrO  NO= 

105*7 

"     "    zinc  - 

ZnO,  N05 

94-5 

Nitric  acid,  first  hydrate  - 

N05  +  HO 

63-0 

Oxalate  of  ammonia,  neu- 
tral - 

NH4  0,  C2  03  +  HO 

71-0 

Oxalate  of  ammonia,  acid 

NH4  0,  2C2  03  +  ) 

116-0 

(binoxalate) 

2H0  j 

Oxalate  of  baryta 

BaO,  C2  03  +  HO 

121-6 

"     "    cobalt  and  am- 

r 

12NH3  +  C6  Co3 ) 

478-5 

monia  - 

012  +  6H0  ) 

Oxalate    of    copper  and 
soda 

C2NaCu04  +  2HO 

116-7 

Oxalate  of  sesquioxdie  of 
iron  - 

Fe2  03,  3C2  03 

1S8-0 

Oxalate  of  sesquioxide  of 
iron  and  ammonia  - 

C6  (3NH40)  Fe2012 

266-0 

Oxalate  of  sesquioxide  of 

C6  Ba3  Fe2  012  +  ) 

582-8 

iron  and  baryta 

21H0  j 

Oxalate  of  sesquioxide  of 
iron  and  potassa 

C6  K3  Fe2  012 

305-6 

Oxalate  of  sesquioxide  of 

C6  Na3  Fe2  012  -f  ) 

347-0 

iron  and  soda  - 

10HO  j" 

154  APPENDIX. 


Oxalate  of  sesquioxicle  of  j 
iron  and  strontia      -  j 

Oxalate  of  lead  - 
"     "    nickel  - 
"     "       "     and  arn-  ) 
monia       -      -      -  ) 

Oxalate  of  potassa,  neutral  - 
"  "  "  acid,  or ) 
binoxalate  (sorrel  salt)  J 

Oxalate  of  soda,  neutral 

Oxalic  acid  j 

Phosphate  of  potassa  - 

"        "  silver 

"        "  soda 
Potassa  - 

"     hydrate  of 

Prussian  blue  j 

Pyrogallic  acid  - 
Kacemic  acid  (see  Uvic  acid) 
Sal-ammoniac  {see  Chloride  j 

of  ammonium)  j 
Silver,  oxide  of  - 
Soda  - 

"    hydrate  of  - 
Stannate  of  potassa 
Starch  -      -  - 
Succinate  of  ammonia,  acid  - 
"       "    sesquioxide  of ) 

iron  j 
Succinate  of  potassa,  acid  - 


Succinic  acid,  crystallized 
Succinic  acid,  subKmed 
Sugar 


of  lead  {see  Acetate  ) 
of  lead)  j 
Sulphate  of  ammonia,  crys-  ) 
tallized  j 
Sulphate  of  sesquioxide  | 
of  chromium  and  am-  > 
monia  ) 


EQUIVALENT,  OK 
MIXING 
PEOPORTION.  | 
HYDROGEN  si,  i 


C6  Sr3  Fe2  012  + 

18110 
PbO,  C2  03 
NiO,  C2  O3  +  2HO 


KO,  C20a  +  H0 
KO,  2C2  03  +  HO  i 

+  2aq 
NaO,  C2  03 
C2  03_+  HO  +  2aq 

=  0x 
KO,  P05 
AgO,  P05 
NaO,P05 
KO 

KO  +  HO  , 

3FeCy  +  2Fe2  Cy3 

+  9H0  _ 
C6  Us  03  =  pG: 


AgO 
NaO 

NaO  +  HO 

KO,  Sn02  +  3H0 

C12  H10  O10 

Fe2  03,  3Su 

C42x2  °3  +  HO  = 

Su  +  HO 
2C4_H2  03  +  H0  = 

Su  +  HO 
Ci„  Hu  On 


NH3,  S03 

NH4  0,  S03  4-  Cr2 
03,  8SO3+24HO 


• 


APPENDIX. 


155 


Sulphate  of  sesquioxide  J 
ot  chromium  and  po-  > 
tassa  ) 

Sulphate  of  cobalt  andj 
ammonia  -  '    -  1 

Sulphate  of  copper  (blue  ) 
vitriol)  ) 

Sulphate  of  copper  and  j 
ammonia  j 

Sulphate  of  protoxide  ofj 
iron  (green  vitriol)   -  j 

Sulphate  of  sesquioxide  ofj 
iron  and  ammonia    -  1 

Sulphate  of  sesquioxide  of  [ 

iron  and  potassa  -  J 
Sulphate  of  nickel 

"      "   potassa,  neu-  ) 

tral  j 
Sulphate  of  soda,  neutral  - 
Sulphite  of  potassa,  neu-  ) 

tral  -  f 

Sulphuretted      hydrogen  j 

(hydrosulphuric  acid)  j 
Sulphuric  acid,  English 
Sulphurous  acid  - 
Tannic  acid  (Tannin)  - 

Tartrate  of  ammonia,  acid  - 
"       "       "      neu-  ) 

tral  j 
Tartrate  of  sesquioxide  of  [ 

iron  - 

Tartrate  of  bitartrato  (or 
acid  tartrate)  of  sesqui- 
oxide of  iron 

Tartrate  of  sesquioxide  of 
iron  and  ammonia   -  J 

Tartrate  of  sesquioxide  of  | 
iron  and  potassa      -  j 

Tartrate  of  sesquioxide  of  j 
iron  and  soda   -      -  ) 

Tartrate  of  potassa,  acid  or  } 
bitartrate  -      -      -  ) 


:1 


KU,  bU3  +  Cr2  (J3,  | 
3S03  +  24HO  j" 

500-8 

(NH4  0,  S03)  +  ) 
(CoO,   S03)  +>■ 
6H0  ) 

197-5 

CuO,  S03  +  5HO 

124-7 

NH40,S03+CuO,  ) 
S03  j 

145-7 

EeO,  S03  +  7HO 

139'0 

(NH4  0,  S03)  + ) 
(Fe2  03,  3S03)}- 
+  24HO  ) 

KO,  S03  +  Fe2  03,  ) 
3S03+24HO  [ 

NiO,  S03  +  7HO 

482-0 

503-2 
140-6 

KO,  S03 

87-2 

NaO,  S03 

71-0 

KO,  S02  +  2HO 

97'2 

HS 

17-0 

S03+HO 

so2 

C18  H5  09  +  8HO 

49-0 
32-0 
212-0 

NH4O,  2T  +  H0 

167-0 

0H4  0,  T  +  HO 

101-0 

KO,  2T  +HO 


156 


APPENDIX. 


NAME. 

FOBMTTLA. 

EQUIVALENT,  OE 
MIXING 
PROPOETION. 
HYDBOGEN  —  1. 

Tartrate  of  potassa,  neutral  - 
"     "  soda,  neutral 

Tartaric  acid  j 

Tin,  binoxide  of  (Stannic  j 
acid                      -  J 
Turpentine,  oil  of 

Uvic  acid    -      -      -  j 
Water  

KO,T_ 

NaO,  T  +  2HO  _ 
C4  H2  05  +  HO=T) 
+  HO  f 

Sn02 

C5H4 

C4  H2  05  +  HO  +  j 
aq.  =  U  t 
HO 

113-2 
115-0 

75-0 

74-8 
34-0 
84-0 
9'0 

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TESTIMONIALS. 


New  York,  October  26,  1S54. 
After  a  careful  test  by  use  of  tbe  Chemicals  of  Heath  &  Brother,  I  would 
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I  have  ever  used.  M.  M.  LAWEENCE, 

No.  3S1  Broadway,  N.  Y. 


Boston,  October  24, 1854. 
Messrs.  Heath  &  Brother  : — Your  samples  of  Chemicals  came  duly  to  hand. 
I  am  much  pleased  with  them.   I  think,  from  their  action,  that  they  are  what 
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J.  A.  WHIPPLE. 

New  York,  November  7, 1854. 
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to  others.  S.  BOOT, 

No.  3G3  Broadway,  N.  Y. 

After  a  careful  trial  of  the  Daguerreotype  Chemicals  of  Messrs.  Heath  & 
Brother,  I  take  pleasure  in  expressing  my  favorable  opinion.  The  Chemicals 
I  consider  superior  to  any  I  have  ever  used.  0.  T.  PETEES, 

Stereoscope  Gallery,  394  Broadway,  N.  Y. 

New  York,  November  S,  1854. 
We  take  pleasure  in  commending  the  Chemicals  of  Messrs.  Heath  &  Brother 
to  the  favorable  notice  of  Daguerreotype  artists. 

GUENEY  &  FEEDEEICKS, 

No.  349  Broadway,  N.  Y. 

New  York,  November  4, 1S54. 
We  have  carefully  tested  some  of  the  Chemicals  of  Messrs.  Heath  &  Broth 
EE,  and.  can  say  they  are  equal  to  any  we  have  ever  used. 

MEADE  BEOTHEES, 
No.  233  Broadway,  N.  Y. 


TESTIMONIALS. 


161 


Easton,  Pa.,  October  12, 1854. 
Your  Chemicals  are  excellent   In  future  I  shall  purchase  of  you,  and  advisa 
my  friends  to  do  the  same.  1  G.  W.  HOPE. 

Ithaca,  September  28, 1854 
Your  Crystallized  Chloride  of  Gold  excels  all  I  have  ever  used.      *  * 
I  shall  use  no  other,  if  yours  can  be  procured 

G.  BAKTHOLOMEW 


New  York,  October  19, 1854. 
For  purity  and  reliability,  I  consider  the  Photographic  Chemicals  of  Messrs. 
Heaih  &  Brother  equal  to  any  others  now  in  market 

M.  B.  BEADY, 
Nos.  205  and  359  Broadway,  K  Y. 

Detroit,  Michigan,  May,  1855. 
Gentlemen :— Your  Chemicals  work  beautifully:  I  am  now  taking  Photo- 
graphs in  the  best  style.   I  shall  no  doubt  do  a  large  business  with  you. 

Yours  truly, 

Messrs.  Heath  &  Brother.  G.  E.  HALL. 


Columbus,  Ohio,  April,  1S55. 
Dear  Sies  :— I  am  taking  better  Photographs  with  your  Iodized  Collodion 
than  any  I  have  before  seen.   Send  me  this  order  by  the  first  express,  as  the 
rush  has  nearly  consumed  the  last  lot. 

Eespectfully  yours, 
Messrs.  Heath  &  Brother,  N.  Y.  H.  LYNDALL. 


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